Tomatillos are in a way similar to tomatoes but Tomatillos have a different taste than tomatoes and also have a husk like outside and are fruity, and slightly herbal in flavor.
Tomatillos are pretty good and are used a lot in Salsa and other sauces and are also great when eaten raw although when eaten raw they have a acidic taste when eaten raw so you may or may not like them raw however I like them in both Salsas as well as eaten raw.