Spectra is a very low stretch fiber. It's useful in situations where low stretch is desired. For fishing, you can feel the fishes nibbling on your bait a lot better. For stunt kite flying, you get better control. For sail handling, you don't have to re-trim the sails as much when the wind strength changes.

However, it doesn't take knots very well. When I use it for my stunt kites, I put a sleeve and a loop on the end to tie it to the kite. I'm sure fisherman do something similar.

Paracord is much more versatile. You can take it apart and use the inner strands for other things. And for most things, a bit of stretch helps make it stronger by cushioning loads when they hit the end. And you can tie knots in it without reducing the strength.