While both paintings depict young women of the time as they're main subjects, there are quite a few differences that one might not notice at first glance. Its glaringly obvious the growth that da Vinci has achieved in his work by looking not only at the focus of the art, but also the background. His earlier work is very lacking in any background while the latter shows off his prowess in painting landscapes as well as portraits. The location of the models attention can also be seen as Leonardo gaining the confidence to allow people to watch him work. "Lady with Ermine" has a very cold color pallet whilst the "Mona Lisa" is bursting with warmth.
As i do not know the precise answer to this i can still give you a big hint. Ok how about you google this and or look up pictures This will most likely help you :)
