What you would consider to be a normal crypto tx is a non-interactive tx

In Mimblewimble, tx data must complete a round trip from Alice to Bob and back (by any means- carrier pigeon is ok) to be broadcasted

This tradeoff results in a ~%50 reduction in chain size and privacy (or a %90 reduction in change size is compared to bitcoin with similar privacy added)

Mimblewimble is the only chain that can actually shrink