Delta IV Heavy is comparable to the (upcoming) Falcon Heavy (though again, due to the capabilities of Centaur, DIVH will be able to fly missions that FH cannot)

Delta IV Heavy is comparable to the (upcoming) Falcon Heavy (though again, due to the capabilities of Centaur, DIVH will be able to fly missions that FH cannot). The Delta Cryogenic Second Stage is not a Centaur. Yes, it uses the same propellants and a related (though not identical) RL-10 engine. The tanks are very different, though, and those are arguably the most unique thing about Centaur: pressure-stabilised ("ballon") tanks made of stainless steel, plus a common bulkhead between fuel and oxidiser tanks make for a very good propellant mass fraction.