Too different to compare. These are all tearjerkers for sure, but in sort of a happysad way, like "so sad that we lost it but so happy that we had it." There is something good and warm that you can identify with, and the hurt comes from it being taken away too soon.

Happy Sugar Life is obvious from the outset that there will be nothing good or warm, there is no hope or anything worth saving. The viewer knows this, but the characters don't. That's what makes it so painful (in a good way) to watch unfold.