There is a chance both of these caterpillars are Monarch's,but one was the standard size,while the other was easily 2 to 3 times larger. The top image is a Monarch Caterpillar,which Im sure of. It was standard 2.5inches.
This 2nd photo,shows another caterpillar which was huge by comparison. Is it another Monarch just huge from gorging on Milkweed,or something different. To my eye the pattern is somewhat different. I realize the close ups dont support my size difference description. Both were taken by me yesterday at Rosetta McClain Gardens in Scarborough.
I have tons of photos at
http://members3.clubphoto.com/frank237849 birds,bugs animals. Enjoy. Thanks in advance BUGFRANK