What is the difference between 做 and 作?
Some real life examples to help identify the differences:

In general, "做" is almost always a verb that has some real meanings. It is very close to English word "do" in its verb form and "make". E.g. "Do your job!" = "做好你的工作!", "do nothing"="什么也不做", "make love" = "做爱", "make some cakes" = "做些蛋糕", etc.

For the word "作", in my personal opinion for now, acts as a function word (虚词) more often than having some real meanings. E.g. "作为" = "as/act as", "装作" = "pretend as". In these examples, it is really close to "as".

One of the most common "real meaning" usages of "作" is "compose": "作曲" = "compose a music", "创作" = "compose/create/write".

Another very common exception of "作" is the word "作文". It is a noun means "essay" or generally the "writing assignments" for students. Without checking it up, I don't even know what exactly "作" in "作文" means.

All in all, "做" is much more widely used as it is really similar as English "make" and "do".