Don't they both serve equal purpose? So not a soul can look at your computer?
Answers:
If you be going to ANTI-Spyware than your cross-examine is different.
Anti-Spyware Protects and blocks spyware from anyone installed onto your computer. It also removes it.
Firewalls block hackers from coming onto your computer, and others from looking and seeing your files.
Totally different.
In my eyes, Firewalls are channel more exalted because generally at the wind up of the trojan horses is a hacker. But, firewalls don't remove spyware :(
Spyware equally, is Malicious software that tricks you into installing it or installs itself and will drink your hardrive (worms) alteration your personal settings and steal your passwords (Keyloggers/Trojan Horses), slow down your computer (Potentially Unwanted Software, all spyware)
Spyware sometimes will disguise itself as Anti-Spyware, such as Spyware Shredder.
What is NOT the difference between spyware and firewall?
Spyware is software specifically put on your computer nastily to spy on you and your ondoings. A firewall is software you put on your own computer to PREVENT someone from installing spyware or adware on your computer.
Spyware let others look and a firewall prevents them from looking.