The MTPdrive allows mapping devices operating in MTP mode to a drive letter in the Microsoft Windows. It offers read access to the files on the device with ability to delete them (e.g. digital cameras or Apple devices). Write access is supported as well but it depends on device's capabilities (typically Android based devices allow it).
The MTPdrive is an evolution of the PTPdrive, it enhances its features (e.g. allows accessing movies in the Apple devices) and also improves usability/performance (accessing original file/directory structure on the device does not require waiting for collecting information about all the files before the mapping can be done).