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I have both. I think the trigger point one is slightly firmer, but I can't feel the different the 'fingers' make.
The main reason I bought it is because it's hollow, so packs more easily into a case. I travel a lot with work.
Well worth getting something to ease out achy muscles in my opinion.
The Grid probably is the best foam roller on the market, its only real disadvantage is that it is only 30cm long, compared to most other foam rollers at 90cm. This means that it is harder to use on your back muscles (especially if you have broad shoulders).
You should choose which roller to get depending on what you want to get out of foam rolling. This article How to Choose a Foam Roller is very helpful.