I had to compare some simple lists. I could have used a database, loaded the lists and used sql to do the comparisons. Not in the mood for that, then let's just use Excel.
We have the following two lists in a spreadsheet and we want to know which of the values in column B exists in column A:

	A	B	C
1	Fusce	Vestibulum
2	mauris	mattis
3	nulla	Fusce
4	pellentesque	consequat
5	iaculis	libero
6	aliquam	eu
7	eu	sem
8	tincidunt	Nullam
9	consequat	iaculis
10	metus	elit

After some digging around in the Excel functions, I found VLOOKUP that does the trick:

	A	B	C
1	Fusce	Vestibulum	=VLOOKUP(B1,$A$1:$A$10,1,FALSE)
2	mauris	mattis	#N/A
3	nulla	Fusce	Fusce
4	pellentesque	consequat	consequat
5	iaculis	libero	#N/A
6	aliquam	eu	eu
7	eu	sem	#N/A
8	tincidunt	Nullam	#N/A
9	consequat	iaculis	iaculis
10	metus	elit	#N/A

In column C it prints the search value if it was found, or "#N/A" if not found. This is ok, but we can make it look a bit nicer by adapting the formula a little bit:

	A	B	C
1	Fusce	Vestibulum	=ISNA(VLOOKUP(B1,$A$1:$A$10,1,FALSE)=B1)=FALSE
2	mauris	mattis	FALSE
3	nulla	Fusce	TRUE
4	pellentesque	consequat	TRUE
5	iaculis	libero	FALSE
6	aliquam	eu	TRUE
7	eu	sem	FALSE
8	tincidunt	Nullam	FALSE
9	consequat	iaculis	TRUE
10	metus	elit	FALSE

Using the updated formula, "TRUE" is printed if the value in column B is the same as the value returned from VLOOKUP otherwise "#N/A" is returned. This in turn is handled by the ISNA function, that's return value is then inverted so that the "TRUE" for "#N/A" is displayed as "FALSE" (the value was not found).