Python dictionary vs list, which is faster?

I was coding a Euler problem, and I ran into question that sparked my curiosity. I have two snippets of code. One is with lists the other uses dictionaries.

using lists:

n=100000num=[]suma=0for i in range(n,1,-1):    tmp=tuple(set([n for n in factors(i)]))    if len(tmp) != 2: continue    if tmp not in num:       num.append(tmp)           suma+=i

using dictionaries:

n=100000num={}suma=0for i in range(n,1,-1):   tmp=tuple(set([n for n in factors(i)]))   if len(tmp) != 2: continue   if tmp not in num:      num[tmp]=i      suma+=i

I am only concerned about performance. Why does the second example using dictionaries run incredibly fast, faster than the first example with lists. the example with dictionaries runs almost thirty-fold faster!

I tested these 2 code using n=1000000, and the first code run in 1032 seconds and the second one run in just 3.3 second,,, amazin'!