The shape of the cross used in crucifixion's changed from country to country- Andrews Cross was indicative of Egypt The others are similar. Northern Africa used a straight piece, where the hands were nailed above the head.
G4716 - σταυρός staurós, stow-ros'; from the base of ; a stake or post (as set upright), i.e. (specially), a pole or cross (as an instrument of capital punishment); figuratively, exposure to death, i.e. self-denial; by implication, the atonement of Christ:—cross.
www.blueletterbible.org
- a cross
- a well known instrument of most cruel and ignominious punishment, borrowed by the Greeks and Romans from the Phoenicians; to it were affixed among the Romans, down to the time of Constantine the Great, the guiltiest criminals, particularly the basest slaves, robbers, the authors and abetters of insurrections, and occasionally in the provinces, at the arbitrary pleasure of the governors, upright and peaceable men also, and even Roman citizens themselves
- the crucifixion which Christ underwent
- an upright "stake", esp. a pointed one, used as such in fences or palisades
The definition is based on usage
When speaking of the instrument of torture and death - it translates to English as cross
When speaking of a fence post or support member - it translates to English as stake.
That is really all there is to the question.