There is no difference between the epoxy in these two products, it is the same. However, there are some differences between the two.
The 9200-25ML contains 25ML of epoxy and the tube comes with a plunger affixed to dispense the epoxy. The epoxy has to be mixed manually prior to application (See datasheet for instructions).
The 9200-50ML contains 50ML of epoxy but the tube does not have a plunger affixed to it. To use this product a dispensing gun ( 8DG-50-1-1 MG Chemicals | Tools | DigiKey) is needed. Another accessory that can be used is a static mixer which removes the need for manually mixing the epoxy. (see datasheet for instructions). The static mixers come in standard 8MT-50(473-1379-ND) and fine tip 8MT-50-FT(473-1378-ND) sizes.