The different tail types is not caused by hard water. Hard water supposedly can cause crowntails to curl their fins, however there's no real hard evidence on that.
Most likely what you are seeing are different types of Crowntails, depending on their genetics. Some people breed CT's with VT's and it makes the CT's tail less spread out and makes them more droopy. Ideally CT's should have a 180 spread like HM's so real CT's are the ones with more of a spread, not that CT's that don't have the 180 spread aren't CT's, they just aren't the ideal specimens is all.
As I said, it may not curl their fins. There is no real evidence supporting that hard water curls fins although it does seem to happen more often in hard water but it could be something else in the water like harder and heavier metals, or calcium, or just more minerals in general. But it's all up to you and what you feel comfortable with. I never had issues with CT's in my hard water but my pH was relatively low and we had very little metals in the water.
I had no idea there was no actual proof of fins curling because of hard water! That being said, my bettas do have some curling and my water is hard. Could it perhaps be something related to what makes the water hard? My pH is higher so maybe that's connected as well?