Yes. Really. But it doesn't have to be.
Manufacturers. Countries. But, probably, mostly manufacturers. There are a lot of letters and numbers and codes on needle packages
What's actually important?
The needle system
The needle size (thickness)
The needle tip
Every needle has those three characteristics.
Somewhere in your machine's manual, and often also somewhere printed, engraved or on a sticker on your machine, is the most basic information you need to know about the needles that will work in your machine. You need to know this information about your machine for this guide to be useful to you. I hope this guide makes the information in your manual more useful too.
You need to use the needle system specified in your machine's manual. But what does that mean?
The needle system is the major (and common) measurements of the needle. Is it a flat or round shank? Almost all home machine needles have a flat shank. How long is it? What is the position of the needle's eye?
Modern home sewing machines all use the same needle system. There are 3 different codes for this system (because of course there are):
130/705
HAx1
15x1
If you've got a modern sewing machine, almost anything since the 1940s, this is all you need to know about needle systems. If you're buying old machines, stick with machines that are labeled to use one of these systems, to ensure you can always find needles for them.
If you have a serger (overlocker) or coverstitch machine, you might have a machine that uses another system.
Many pre-1995 overlockers use other needle systems. If you have a serger that uses DCx1F or JLx1 needles, you'll know that. If you don't, don't worry about them.
Modern coverstitch machines may need ELx705 needles. They're very similar (same shank, same length, same eye position) to 130/705 needles. But for coverstitch, you need the slightly different needle to ensure your machine forms that complicated stitch properly. 130/705 needles will fit in the coverstitch needle clamp and not break the machine, but will probably drop stitches.
If you have an industrial machine, a semi-industrial or a long-arm quilting machine, you definitely have a machine that uses another system, but you're unlikely to need a beginner's guide to needles.
Once you know your needle system, you need to answer the question of appropriate needle size. Heavier materials, thicker needles. Lighter materials, thinner needles. Simple, right?
Well, yes, but they make it complicated. There are two needle thickness numbers. You might see needles labeled 80/12 or 100/16. The first number is the metric measurement in hundredths of millimeters. "100" is a 1mm thick needle, 80 is a .8mm thick needle. The other number is the Singer number. It's a lot less meaningful, but each increase of "1" in the singer number is an additional .05mm of thickness.
At least it's still smaller numbers, thinner needles and larger numbers, thicker needles.
So lighter materials, smaller numbers, thinner needles? Heaver materials, larger numbers, thicker needles? It's that simple, right?
If you only ever use "standard weight" sewing thread, sure. But if you use heavy or decorative thread, it might not fit through the eye on thinner needles. It's all about matching your material, your thread and your needle.
Heavier thread, larger numbers, thicker needles too. Some thread vendors (like Superior Threads) may recommend a needle size for a specific thread.
You've got your sharps, you've got your universals, and you've got your ballpoints. These are the normal ones, at least.
Universal needles are "sew most of the materials" needles. They've got a small but slightly rounded tip. Small enough to feel sharp to your finger, round enough to push threads in the fabric around the tip rather than punching through (or cutting through) the threads.
Ballpoint needles have a more rounded tip than universal needles. They're for knit fabrics, where a sharp needle or a universal needle could break a thread in the fabric and create a run.
Sharp needles have actual sharpened tips. They're useful on tightly-woven fabric, and also really fine fabric. Most needle manufacturers label their sharps as "Microtex" now.
Sticking to these basics should simplify things a bit. You probably only need to know one system, and know that the 3 different names are all the same. Being able to pick different needle sizes and tips for your materials isn't difficult to learn.
And if you buy bulk needles made by Organ (one of the largest needle manufacturers, headquartered in Japan but with factories all over Asia) from somewhere like wawak.com or allstitch.com you can get standard HAx1 needles (the code Organ prefers) for around a dime each. The more you buy, the bigger the discount. You don't have to spend a lot of money to keep a wide assortment of needles in stock.
That's really great, because needles are consumable items. Industrial shops replace their needles every 8 hours of use, but that is 8 hours of constant sewing. You're probably not going to wear out needles every day unless you're running your own assembly line. One of the more reasonable guidelines is "New project? New needle."
The last thing you want is to ruin a project or waste a ton of time because you didn't replace a dull or damaged needle that only cost you a dime.
There are all sorts of specialty needles, and you might need some of them. They tend to cost 2-3 times as much as basic needles do.
Microtex are just sharps, but I'm mentioning them here because they're usually specialty priced. They're an excellent choice when sewing really fine, light wovens.
Superstretch needles are available in universal and ballpoint tips. They have a "cobra eye" that flares around the eye, helping the thread pass through athletic fabrics like lycra. If you're sewing with lycra, you need these.
Leather needles have a "chisel point" to cut through leather and other non-woven materials. If you're sewing with leather or vinyl, you need these.
Anti-Glue needles are non-stick coated, and are fabulous for sewing through materials like neoprene. If you're sewing with sticky materials and interfacings, you need these.
Topstitch, Embroidery and Metallic needles have a large eye and a larger groove, so you can use flashier, thicker decorative threads.
You might not need all of them.
Jeans/Denim needles are sturdy medium ballpoint needles for stitching heavy canvas, duck and denim. But are they really sturdier than the same size universal needle?
Jersey needles are ballpoint needles for, you guessed it, sewing jersey knit. But they're not really different from any other ballpoint needles.
Wing needles are broad, flat needles used for "heirloom" machine hemstitching. They're weird and only useful for a few techniques, and you probably don't need them. If you do need them, you don't need a beginner's guide to needles.
Quick-threading needles have a notch in one side of the eye so you can just slot your thread in. But you need to sew slowly to prevent the thread from popping out and the needle from breaking. You would probably be better served by buying a needle threader.
Titanium needles are titanium plated, and claim to last longer than normal chrome-plated needles. They also cost more. A lot more.
If you want to learn more about needles from the manufacturers, Schmetz and Organ have excellent needle guides to tell you all about needle anatomy.
Some manufacturers paint colored bands on needles to help you figure out what needle you're looking at. This is great. There's no standard for color bands. This is terrible. Color codes can be incredibly inconsistent. Schmetz needles use a 2-band system, one band for tip, 1 band for size. Organ only color-codes some needles. Needles made for sewing machine companies may be color-coded in different ways than the manufacturers code needles sold under their own brand. Organ makes Janome needles, but Janome color codes are unique to Janome needles.
Bulk needles often have no color codes, because industrial users start with fresh needles every work shift, and always use the same size and point each shift.
If you learn the numbers and the points, they're going to be consistent across brands.