Garmin 1242xsv versus 1242sxv Touch

[Photolomy]

Is the only difference between these two chart plotters, touch? Also, when you install the thru hall transducer, do you typical go with a single transducer in the keel, or a pair of angled transducers on the sides? The boat (53 MY) will be out of the water, so I thought I would get that done while it is out.

Edit: The title was supposed to be 1242xsv versus 1242xsv Touch