I'm not sure how to answer. What colors are you seeing? Your 84 that looks like the cookie monster has attacked it is zinc rot, as Sal mentioned. The 73S looks like a nice standard brown cent from the photo... Is there a part of the cent you're seeing different colors at?
No I was just teasing...it looks like someone tried to clean them up and took a little color with them.
Hilarious? Maybe in your mind. New members with no collecting experience, and no knowledge of the minting process, will only be confused more with answers like this, especially when they read what is under your avatar and confuse you with someone who knows what they are talking about.
They do seem to be a bit unnaturally orange, as though cleaned. The zinc cent ("Zincoln", if you will) does, as mentioned, suffer from zinc rot. Zinc is a terrible metal for coinage. Even plating it with copper, as the US has done since 1982, does not always seem to prevent the corrosion, as we see here.