3D cards are usually more based around OpenGL where as gaming cards are more Direct X.
There are plenty of gaming cards that work fine with 3D and some that have little quirks that can usually be worked around.
Although Workstation cards are not specifically designed for gaming they too can do a fine job depending on which card and price range.
In my opinion Nvidia cards seem to have less problems with 3D in general although I 'm sure there are exceptions.
Autodesk has list of compatable cards for Maya although just because a card is not on the list does not mean it will not work it's just that they have tested listed cards and those cards and are known to work.

Here is the link
https://usa.autodesk.com/adsk/servlet...112&id=9683256


The truth is you can do both things with both types of cards but sometimes the odd model number will have glitches with what you are doing.
If 3d is a hobby and you do lots of gaming then there is nothing wrong with getting a gaming card for 3d,although once you decided on a make and model a quick Google to see if it has issues would not go a miss. If you intend to make 3d a career then a workstation card is a must i feel.