From Lexicanum

Tank	Super Heavy Tank - Heavy Tank - Grav-tank - Battle Tank - Tank Destroyer - Air Defence Tank - Armoured Personnel Carrier - Artillery Tank - Siege Tank

Heavy Tanks are Tanks used by the Imperial Guard but which are smaller than Super Heavy Vehicles. They also count as War Machines.

Types of Heavy Tank

• Macharius: A Battle Tank.
• Malcador: A Battle Tank.

Sources

• Imperial Armour Apocalypse