There are 5 types of Heroes you can gather in the game. Beyond their shapes, you can recognize their types by their overall colors.
Pink Heroes: "Diggers"
The Pink Heroes family are feisty diggers and will destroy 4 rows of dirt when they reach the speed required to break blocks.
Blue Heroes: "Bouncy"
The Blue Heroes family are bouncier than the other ones. They bounce more off the ground and off the walls.
Red Heroes: "Stompers"
The Red Heroes family are heavier than all the other ones. They fall faster and will also reach the speed required to stomp and break blocks faster.
Yellow Heroes: "Striders"
The Yellow Heroes family are the fastest horizontal movers relative to their size.
Green Heroes: "Sliders"
The Green Heroes family are sliders. Maybe it is because of their slimy skin but all the Heroes in that family seem to slip more on every surface they touch.