A Tardis is a time machine that a Chronogod would typically use. Like many Chronogod technologies, Tardes are famous for breaking the laws of physics by being bigger on the inside and smaller on the outside.
The Phone Box
The Phone Box is the Doctor's Tardis. He stole it when he was 21 and has since used it to travel all over the universe to make it a better place to be in.
The Master travels through time in an RV that always takes a new form (such as a fridge, a clock, a column, or a fireplace) whenever he moves to a new place and time. The Master uses this as a vessel through which he can take over the Multiverse.