Both have MCs trapped in a world that's suddenly and inexplicably overrun with extremely dangerous monsters. Both have the MC affected by those monsters in a way that's advantageous. The MC of both stories are also pretty similar in personality and the way that characters grow and interact is pretty similar. I'd say Surviving Romance focuses more on the horror and survival elements throughout it's entire run, even though characters get stronger the monsters also get much stronger (so far, might change in the future as SR is not finished yet and bc it involves time travel;) whereas Sweet Home shifts more to focus on the interaction between the main group and this sudden villain group in it's later chapters because once the main characters in SH are well equipped the monsters stop being so threatening.