Seeing someone usually applies to the beginning of a new relationship. It usually indicates a heightened level of interest, and even offers subtle speculation that it may turn into a serious, committed relationship. Dating tends to imply that the relationship has grown into a much more serious endeavor.

What does it mean seeing each other?

Seeing each other, means that you are involved with someone. Youre not necessarily exclusive, but youre interested in the possibility. Think of it as seeing about someone. If youre seeing someone you can still be dating others.