They feel totally different. Temazepam is a different sort of benzodiazepine. It is commonly used as a sleep agent (not typically prescribed for day time use), as it is a hypnotic agent.
http://en.wikipedia.org/wiki/Temazepam
Valium is more of an anti anxiety drug whereas temazepam is more often a sleep aid, a tool to treat insomnia or trouble sleeping. Diazepam has a longer half-life, thus temazepam is out of your system faster. If you take it, give yourself a good 7-8 hours (where you don't need to drive, etc.) as it'll make you unable to perform such tasks (if taken at a dose that is not super low... ) *or, you should NOT be doing those tasks, even if you 'feel' like you maybe would be able to*
Check out the wiki info on temazepam - I find it pretty interesting - comparing the use and abuse of the substance across the globe. I am prescribed temazepam for sleeping - it works wonders! Tolerance builds fast. I'd never take it during the day if I want to function (and thus, I never do). I do however take all and any other benzo (am prescribed lorazepam, clonazepam currently and was previously prescribed alprazolam.) I have also taken diazepam via a friend -- I find valium to be the benzo 'easiest to function on while maintaining a certain glow' of the lot. Clonaz/loraz are great for day use as well... but those are not related to this thread
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Temaz is a bit 'heavier' in my opinion. It's almost like a VERY light opiate-like glow + benzo sedation (never found benzos 'fun'). Valium is just relaxing, plain and simple. However, valium won't (straight up) put you to sleep. Temazepam, for me, is not a 'take and go about your day' type benzo, whereas valium is. That's that!