The frogtie is a bondage position in which a person's legs are bound ankle-to-thigh, in the likeness of a crouched frog. The wrists on each side are often then tied to the wrist/thigh combination on their respective sides.
This tie places the person in a position where they are vulnerable but not completely immobilised and can still move about, albeit in a very awkward crawling motion. The frogtie, with the person restrained so, can also be used as a restrictive sex position or as a basis for more restrictive bondage.
In a similar position, the person's wrists are simply bound to their corresponding ankles. However, that position cannot be fully considered as a frogtie, because it does not match the "bound ankle-to-thigh" condition.