I wouldn't know the different types of thread if someone dropped a Thread for Dummies book on my doorstep.
I tend to use all-purpose because I'm hoping it's safe for general use. I use it for piecing, top and bobbin. Don't do a lot of machine quilting, but when I do, I use a pretty variable color on top and bobbin.
I'm always interested in buying thread though. My sil bought me a really pretty sewing caddy last year. It came with 40 spools of the crappiest thread I've ever seen. I only use it for buttons or something where I don't need a decent quality. I'd like to throw the whole lot out, but then I'll have this pretty caddy that's completely empty.
Pardon the grumblings......
~M~