With the 450 and the 550 business and so on.... be advised.
All Paracord depending on who makes it is on their own companies standard (yes they have a set of specs but its up to them how they get there), unless of course its military grade but even then its just by strength.
What I mean by all of this is that 450 paracord is nice to use as its normally a smaller diameter (because the housing is smaller) with the inside cords removed.
However your 550 can be one of two kinds. It can be the same 450 diameter with more cords stuffed in, or a slightly larger diameter and also vice versa.
That being said, when I looked a little while back 450 was hard to find in many colors. But 550 comes in lots of colors and easily available.
Also be on the lookout for some makers that produce poor (fuzzy and tangled) Paracord, as its useless and basically needs to be thrown away.
Hope some of that helps.