No mega technology advances really. The light framed Glocks are the same basic design internally. The heavier recoil models include an extra pin in the forward part of the frame.
Newer Glocks, including newer 17Ls, have a different breechface angle.
Internally the 17, 17L, and 34 use the same parts. The barrels, receivers, and slides have different part numbers.
The 17 and 34 use the same mags.