Sometimes those different lines for the same room size is correlated with the different check-in days of the underlying week. At the resort, there may be a portion of the weeks that are designated for Friday check-in, some Saturday, and some Sunday.
Normally, this doesn't matter one bit when choosing your reservation (as you have seen). The only place where it does make a difference is if you are making a reservation over the weekend where there is a season transition (from Gold to Platinum, for example). In that case, the Friday night of the Friday check-in week / line may be in the "Platinum" season, where the Friday night of the Saturday check-in week / lin may still be in the "Gold" season -- and cost fewer points.
I hope I explained that well enough. If you search out those season transition times, you can check it out for yourself. But bottom line: most of the time it doesn't matter which room you book if they cost the same points.