Interesting. Some observations:

TextSecure has been a work in progress for two years: https://github.com/WhisperSystems/TextSecure/commits/master?...

Telegram seems to have been in progress for two months: https://github.com/ex3ndr/telegram-mt/commits/master?page=2

Telegram also seems to be the work of a single author. While TextSecure was written mostly by Moxie, there were several other contributing members.