Game computer graphic cards are designed specifically for handling high demand dynamic graphics. Where as engineering graphics cards are designed specifically for high resolution, fine pixel and most importantly, being compatible with all graphic functions of CAD/CAM/CAE software.
I have found that one can use a high performance video game graphics card with CAD, however there always seems to be a higher number of crashes and other related graphics performance problems.
It is probable that the engineering graphics card is more expensive due to less demand for the graphics card. In general, I would stick with a graphics card that is specifically compatible with your CAD software and related hardware.