As far as I know, there is no such word as "alot."
lots means lots of one certain thing, a lot means a lot of many things
"alot" is not a word. The proper term is "a lot" for all words.
Should you use "lots of" or "a lot of" in a sentance?
'Alot' is not actually a proper word, and cannot be found in any dictionary, but people use it as a quick way of writing a 'A lot'.