No, not at all. Seroquel is an anti-psychotic drug with nasty side effects, including permanent neurological damage and death. The withdrawals can be severe, but they only last about six weeks or less. It is highly sedating, which is why it is sometimes given for sleep. It is fairly easy to quit if you don't mind not getting any sleep for a couple of weeks.
Xanax is an anti-anxiety drug, and it does a most wonderful job of turning down the anxiety. Unfortunately, there is a severe price to pay for that, as it is hellishly addictive, and the withdrawals can last for a couple of years (yes, YEARS!). You can develop tolerance to it real fast and you will need more and more to do the job. It is very difficult to quit taking if you have been taking it for a while.