MirageOS is similar to Docker but without Linux as the underlaying.
It creates unikernals which assemble the application along with the parts of the OS that are needed for that application.
Unikernels are drastically smaller that Docker containers.
The spin up and tear down of MirageOS instances is so fast that they could be created within the time of a HTTP request.
Unikernels being smaller (less OS code) ahve smaller attack surface area.