>Protagonists are in their mid-late 30s. (Both of them are also named Satoru lol) Both are also virgins who never had a girlfriend.
>They're both overpowered.
>Both have extremely loyal subordinates.
>Both of them build a country from scratch.
>Both are good natured people but take extreme action when needed.
>Both have the potential and ability to create a harem, but refrain from doing so for valid and personal reasons.
>Both of them unknowingly/accidentally end up doing incredible things.
>Overlord is more dark themed while TenSura is more light, with occasional dark theme spikes.
>Rimuru prioritizes friendship and good ties more than overpowering new acquaintances.
>Momonga is overpowered from the start and has no power growth, whereas Rimuru is overpowered only in his vicinity and has to grow to keep up with increasingly powerful enemies.
>TenSura protagonist dies in his old world whereas Overlord protagonist (most likely) does not.
>The New World in Overlord is more game-like (levels and such) than the world in TenSura
>Momonga is an overbearing undead skeleton while Rimuru is a cute harmless looking slime.