Recommended ads VS other - square ads

I wonder what the difference between recommended ads and other ads are?

http://ift.tt/1eBkWlR

I would love to have the medium rectangle (300x250) ad on my side column but the side column would be to big for my site so I have to go with the square (250x250) ad which is not under the recommended ads. How will using the 250x250 square ad affect me? is it a bad idea using the 250x250 compared to the 300x250, etc?

from AdSense http://ift.tt/1XvBoeK
via IFTTT
Thanks for your comment
Loading...