The soft and hard waxes are pretty much the same consistency as each other, however, the hard waxes are slightly harder, as the name suggests.
The difference between the two is that in principal, the soft wax is easier to apply and easier to buff off and gives a more glossier finish. The hard wax is harder to apply and remove, but will give more durability than the soft wax.
To be honest though, when you're looking at waxes at Dodo level, they're all good performers so really, you can't notice much difference between the two. It's only when you're looking at the real top end waxes that you'd notice a massive difference between them.
Hope that helps
Taryn and Jim
