It is an anti-malware/spyware/adware program,
While most attack currently are those styles of programs virus's are still quite prevalent.
An anti-virus program is written to detect virus's and in some cases common spyware,
An anti-malware program is designed to detect malware,
you get the idea?
Trusting one program to do everything is like trusting your routers firewall...
It just doesnt block/catch everything.
Multiple layers of protection are the key.
Your pc firewall.
From the end user to the internet,
Hopefully one of the layers will catch the baddies before they get to you and your information.