I know some people are going to look at this post and think, "this has nothing to do with the title and that was 2 mins of my life I won't get back!" sorry to those people but for the ones still reading I'm not that familiar with Primes and wondering what the difference is.

I have read recently that a prime lens is a fixed focal length say 50mm, 28mm, 200mm etc does that apply to all fixed focal length lenses? I have the 60mm f/2.8 D and have been reading about the new 50mm f/1.8G that has great bokeh and is great as a portrait lens and then there is the 40mm on the horizon, apparently!

What I would like to know is; My 60mm is known as a macro lens and that's what I use it for, underwater macro actually is it the same as the 50mm besides the obvious difference in one being 1.8 and the 2.8, are they both a macro lens or is one specifically designed for macro and the other for portraits? I am asking because I was wondering if there is enough of a difference between the two for me to go out and purchase the 50mm for portraits? Or should I just use my 60mm macro and move a little bit further back than where I would stand if I had the 50mm? I understand that the 50mm 1.8 is going to be a lot better in low light and faster? Just slightly confused that's all lol

Anyway, hoping someone can clear this up a little bit for me?

Thank you in advance