Whats the difference between spontaneous fission and radioactive decay?

[BTruesdell07]

I was doing some research on Technetium and I found out that it occurs naturally in uraninite from the spontaneous fission of U-238. But on the decay chain of U-238 I can't find Tc any where... So what's the difference between spontaneous fission and radioactive decay?

 

[chemisttree]

Spontaneous fission is to radioactive decay as arson is to fire.