What are Dwarven Cogs?

Solution 1:

In The Elder Scrolls franchise, Dwarves are an extinct sub-race of elves (the species of which is collectively known as "mer").

So "Dwarf" is to "Dwemer" just the same as "Dark Elf" is to "Dunmer" or "Wood Elf" is to "Bosmer".

So if someone told you to collect "Dwarven Cogs", they really meant for you to collect "Dwemer Cogs", found almost exclusively in the assorted Dwarven ruins.

I assume you're doing Arniel's Endeavor? UESP says you're looking for Dwemer Cogs, despite the quest text.

The biggest issue of course being:

Currently the Quest tracker will not track it when you pick up a Dwemer Cog, however they still count for the quest, so you must keep count of them yourself.

Solution 2:

If you are talking about the quest from Arniel Gane, yes Dwarven Cogs are Dwemer Cogs.