And 2024-t3 is much more “tough” - toughness, strength, strain…all related, but different.
To add to What @DanoInTx points out, the different processes result in different grain structure in the metal, which then has different properties. Crystal shape and stretch have a lot of impact on how the material behaves depending on what you’re going to do with it next - press forming, machining, welding, further heat treating post machining, etc.
In general, 2024-T3 is the most common 2024 you’ll find in the US. It’s not weldable because the welding operation messes up the grain structure. You must not weld 2024 if you’re using it for it’s specific properties. 2024 is great for riveted structures, highly corrosion resistant, and very strong. 2024 tends to be on the more expensive side. 2024-T3 is the go-to material for light aircraft. I’ve never found decent sized scraps of this anywhere, and never found it in anything but sheet and small dimensional shapes (angles, small tubes, etc).
6061-T6 and 6061-T651 is super common, and has totally different machining properties - much easier than 2024. You can anneal 6061, do beautiful shaping operations on it - it gets almost flimsy, then re-harden it. 6061-T651 has a lot of internal stresses that 6061-T6 does not - therefore if you heat treat 6061-T651 after machining, it’ll get all out of shape and twist. 606x alloys tend to be cheaper. A cut piece at the yard will look pretty “clean” without gummy chips welded to the cuts. If it’s a biggish block at the scrapyard, it’s very often 6061-T6, but if not marked, you can’t tell for sure.
5052 is generally easy to weld, but kind of gummy to machine. I don’t like machining it, and it’s generally cheaper than the others. If it’s not marked, with my luck, it’s probably 5052. If you’re looking at a cut piece at the yard, and the cut looks “gummy” - it’s 5052. I hate this stuff.
Cast aluminum (MIC6, there are a few brand names) has a very different internal structure (and that’s why it’s stays so flat) - and machines beautifully.
There are some brief, but clear descriptions of the various grades over here: https://www.onlinemetals.com/productguides/aluminumguide.cfm