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Pro Textures the model
Pro Uses high power servers
The fact that it's not your phone actually processing everything by itself means you will get much faster and more accurate results as the phone is not doing the heavy work. This also means that just about any device including low end ones can take advantage of the app.
Con Uses internet
The fact it uses online servers means you will end up having to send them a pack of high definition pictures, using up a users data. This also means the app will not work if there is no internet connection at the time of use.