[pvg]

I don't think your wikipedia link supports the assertion that institutions and bureaucracy changed very little. Even 'continuation' is fairly shaky since, as the page itself points out, unlike the subsequent Ottoman one, the Byzantine empire wasn't much of an empire by the time the Ottomans took Constantinople (and for quite a stretch before that).

[rnmwfQ3f]

The Ottomans were already ruling most of the Byzantine empire by the time they took Constantinople.