TARDIS, Type 40 Mark I TT Capsule
The TARDIS that the Doctor stole was a Type 40 Mark I TT Capsule from Gallifrey. The Time Lords used it to travel through space and time. Although their official name was a TT Capsule many Time Lords referred to them as TARDISes.
Time and Space Vehicle
Susan clearly stated in An Unearthly Child that she made up the name TARDIS from the initials Time And Relative Dimension In Space. However it was later suggested that this was a common name used by all Time Lords to describe the machines.
The TARDIS, also known as a TT Capsule was the main kind of time and space vehicle used by the Time Lords of Gallifrey.
Stealing a TARDIS
The Doctor was shown stealing a Type 40 TARDIS from Gallifrey in The Name of the Doctor. A row of cylinder shaped structures were shown, presumably the cylinder structure was the default style for TARDISes/TT Capsules.
SIDRAT – Space and Inter-Dimensional Robot All-purpose Transporter
SIDRATs could be considered as earlier versions of TARDISes, the Time Lords stopped using them due to their limitations. SIDRAT was an acronym for Space and Inter-Dimensional Robot All-purpose Transporter. The SIDRATs couldn’t change their appearance, their default shape was similar to the default TARDIS shape. Like TARDISes the SIDRATs interior is larger than the exterior.