There are differences, though, and we don't just mean in size. The grille is taller, more upright, and more squared off. In fact, the whole SUV looks more upright and squared off. The C-pillar contributes much to this, since it's close to being vertical, and it's more integrated with the window area, whereas the pillar on the GLE-Class looks like it will stand out on its own.
The new GLS-Class will likely keep a similar powertrain lineup to the current model. A twin-turbocharged V6 will probably be the standard engine, with twin-turbo 4.0-liter V8s in varying states of tune for the higher-trim and AMG versions of the SUV.