not really, they are just from different companies. losi and ae can't use the term cvd because mip ownes it(i checked) so if a kit has that type of axle, they just call it a cva. You can tell because they all look the same.
Mip cvd:
http://www2.gpmd.com/image/m/mipc1525.jpg
Cva:
http://www2.gpmd.com/image/o/ofnc9026.jpg
And some new kits are starting to downgrade. they actually use the not-as-smooth universal joint.
uvj:
http://www2.gpmd.com/image/o/ofnc1510.jpg