raman & Waldo are right.
Cleaner and avast! are completely different programs that have absolutely nothing in common (except they're trying to fight viruses somehow
Cleaner is a simple standalone tool able to disinfect specific viruses from your computer. It can only handle the viruses listed on the corresponding web page / in the About box, i.e. a very limited number. It doesn't have any resident protection, it doesn't scan inside archives, it doesn't have any online updates.
On the other hand, if you are really infected (by one of the viruses from the list), Cleaner should be able to disinfect your computer in any situation, e.g. when the virus is active in memory - no need to reboot to safe mode or anything like that. Just run it and let it do its job.
Btw, compare the sizes of both the programs: Cleaner has 220kB (and in fact, it includes 2 identical program versions inside - ANSI and UNICODE), avast! Home has 6.5MB...