In MVP a Presenter has reference/access to the View, i.e. you can directly bind to Click events or call a control's method from the Presenter. In MVVM this isn't allowed, as this breaks it.
This means, the Presenter in MVP is tied to the view and can't be reused across different views (MVVM there is usually 1:1 reference between VM and View) or between different Applications (WinPhone, Desktop, Xamarin, Silverlight versions) and that the Presenter is responsible for reading and updating the View (when a value changes). In MVVM, the View (via binding) does this synchronisation, the VM only "notifies" the View when a value changes