The Sony E-mount is designed for Sony mirrorless cameras. E-mount was released in 2010. Compared to Sony A-mount the flange distance is much shorter, only 18mm, therefore many lenses can be adapted to be used on the Sony E-mount. Nearly all manual lenses can be attached with simple metal adapters and Canon EF(-S), Nikon F, Contax N & Contax 645 AF lenses can be used with mount specific smart adapters with true electronic integration allowing EXIF data, autofocus, image stabilization etc.

The Sony FE mount is not different from Sony E but FE is used to nickname full-frame cameras and lenses with full-frame coverage. Be careful when buying lenses for your full-frame Sony E cameras, as it is not always obvious which are full frame and which are not.