And I remember a time where I was confused enough already on thinking about the difference between the few carbines I know of like the XM177 or the 733 and then I find out there are more

There are dozens of variants in the Colt catalog alone. And that's not counting all the Franken-ARs that have been put together, both in the real world and in movies. Some of them simply don't have a specific model number.

I've seen them too. You have to be an AR-15 fanboy to know exactly what model you are looking at and of course for the franken guns you need to know a lot to recognize what is mashed up with what

What, does someone need me to identify an AR? :p

We'll keep you on speed dial if we come across something of interest