I have to put in two 240v 30a outlets, and plugs.

Is there a difference between 10-30 and 6-30? My limited understanding is
that 10-30 has a neutral and 6-30 has a ground, and since my application has
a ground, 6-30 should be correct, but does it really matter since I am doing
it all from scratch? HD has the 10-30 cheaper, and they don't even have
6-30 plugs. (my dryer circuit has an "uninsulated neutral", which I would
have called a ground...)