No offense, but the answers here were either wrong or incomplete so I decided to look it up. For those who want the gist of the situation:
An unlocked bootloader allows for the booting of kernels that are not signed by HTC (and probably jointly the carriers).
S-OFF disables write protection on the /system and /boot partitions. It is part of the NVRAM of the radio and is patched during HBOOT, which I believe is HTC specific.
An unlocked bootloader allows for the booting of kernels that are not signed by HTC (and probably jointly the carriers).
S-OFF disables write protection on the /system and /boot partitions. It is part of the NVRAM of the radio and is patched during HBOOT, which I believe is HTC specific.
sources: http://alpharev.nl/