Please note that the effect of "Ultimate Ancient Gear Golem" states:
If this card is destroyed, you can Special Summon 1 "Ancient Gear Golem" from your Graveyard, ignoring the Summoning conditions.
Now if it said "1 "Ancient Gear Golem" monster" then you could, but all it specifically says is 1 "Ancient Gear Golem".
This means that you can only Special Summon "Ancient Gear Golem". I hope this explanation helped you understand the difference.
Screw the money, I have rules!