There's currently a tag brick-and-mortar as well as live. Similarly there are tags online-poker and online. There are other possible variations that haven't happened to come up yet ("live-poker" for instance).
So I think it's pretty clear that there are two major categories here and that we need synonyms (brick-and-mortar / live should be synonyms and online-poker / online should be synonyms). However, which names should be the main names? Are there other synonyms we need to worry about?
I think a large portion of questions will be tagged with one of these two, so it's important to do this right. I also think questions that relate equally to both can be left without one of these tags, but if you disagree you can include why in your answer.