The only difference is the portafilter and portafilter basket.

The Regular 107M is equipped with a pressurised portafilter and basket. This is recommended for first-time users of espresso machines as it takes care of the parameters of tamping and creating the adequate pressure for achieving the perfect espresso shot.

We recommend you go in for this model as it is a great entry level product.

The PRO 107M is equipped with a non-pressurised or bottomless portafilter and basket. This is recommended for coffee enthusiasts who prefer to customise their espresso experience and are willing to undergo the learning curve to achieve the right tamping technique for creating adequate pressure for the perfect espresso shot.

We recommend this for home baristas only.

Here is a link to an article which has more information on non-pressurised or bottomless portafilters.