"There's no point in discussing this." means that it is useless to continue discuss whatever you're discussing. For example, there is no point in two people with strongly opposed opinions (such as pro-life or pro-choice people) to discuss the issue of abortion because they will almost always be opposed to each other and rarely change their minds. "There's no point to this discussion." means that there is not point to the discussion. The discussion is aimless. It's like a movie without a plot.

There's no point in discussing this. = Nothing good will result from talking about this topic. There's no point to this discussion = There is no identifiable topic of the discussion.

"there is no point in discussing this" means that it is pointless to discuss an issue just one issue, while "there is no point to this discussion" means that the whole discussion is pointless, you may be discussing a lot of issues at one time.

I agree with Legtz

not same :P