One of the biggest differences that effects everyday life, I'd have to say, is the differences in signs- public transportation, street signs, warning signs, etc. Some are only little differences, but some are HUGE!
For example street signs: they aren't posted on curb corners, they are little plaques on the corner of buildings. Problems with this, not all buildings are available to be posted on, so there are no signs at some corners. Also, you have to walk right up to it to read it, so from far away you can't tell you are going in the wrong direction until its too late.
Here's a picture of a no parking sign on the Seine...I thought it was funny to see traffic signals on a water way. Yeah, I'm from Texas.

This one is, hands down, my favorite sign EVER! I don't know why, but every time I see it I can't help but laugh.