How sad, but at least you saved some pieces:). Sometimes these Cereus can be hard to id because they look different, but all get put under Cereus peruvianus:). Read This;). That post I could not agree with more:).

So you could easily call them both Cereus peruvianus and be right:).

From what I can tell the top one looks to be monstrose. They can still be vertical and be monstrosed. Crested or cristata is more wave like.

This is Cereus hildmannianus subsp uruguayanus monstrosus. Pic from Dave's Garden. I believe this is the true id of your top plant;).

This pic is from a site called Horticulture Unlimited. They have it labeled as Cereus peruvianus f. monstrose.

Pic from llifle, which has this one labeled as Cereus hildmannianus f. cristata monstrousa.

Ok now the bottom one I would call Cereus repandus.

Take everything I said with a grain of salt because Cereus peruvianus has sooo many synonyms and tons of contradicting info;). When it gets cooler I would put styrofoam cups at the ends. Just to protect the center growth.

I finally put mine in ground a month ago. Poor thing was in a container for like two years.

A house I use to drive by had a nice and old succulent/cactus garden in front. Well one day I drove by and noticed the sheriff took over the house. They had most of the cactus cut down. All that was pretty much left was Euphorbias.

Wow thank you for the IDs and info! That would make sense as to why I see labeled cereus peruvianus at nurseries and there is always so much variation among them.

Your cereus looks very healthy! I have a potted one as well that is not nearly as thick and robust. I think mine needs more sun, I've had it in shade mostly.

Are the styrofoam cups to protect the growing ends from excess moisture collecting in the center?

Same here. I will see cactus labeled with the Cereus peruvianus name, but they look very different. The styrofoam cup is to protect the growing tip from frosty nights:). These Cereus I've noticed look better when receiving good water and not getting beat up by the sun. They will loose that pretty blue hue and shrivel up. They can handle the abuse, but don't look as nice;).

Normally I would say don't try to root a cutting now. Especially outside, but these guys it does not matter. They grow fast:).