[qwertyboy]

It looks like TextSecure encrypts your actual texts, for which you still pay, while Telegram also takes care of delivery, for free, and does it faster and better than SMS (which should be pretty darn easy, what with SMS doing such a very bad job indeed).

[BuildTheRobots]

(iirc) If you're communicating with another TextSecure user then the messages go via the internet rather than over SMS

[floatboth]

If you're communicating with a CyanogenMod WhisperPush user.