Force carbonation bubbles vs. bottling

[rcd]

I started using kegs a few months ago, and that's worked out fine, but I've noticed that when I force carbonate, the carbonation is super fine (the bubbles are super tiny, almost invisible unless you tilt the glass and see them for a moment). The other day, I opened a bottle of some beer I'd made when I was still bottling, and the bubbles were much bigger, more along the lines of what you see in a commercial carbonated drink.

Is this normal or am I doing something wrong when I force carbonate in the kegs?