what is difference between penalty corner and penalty stroke?

It might depend on the sport you're playing. In field hockey, in a penalty corner (which takes place if a foul occurs inside the circle), the team taking the shot has players line up around the circle in front of the goal, while some go back to the 50, one takes a small hit from the end line to someone on the circle and they try to score a goal. There are 4 defensive players from the other team in the goal with the goalie and when the ball is hit, they run out to block those players who are around the circle, and the rest of the players run back from the 50.

A penalty stroke is when a foul occurs anywhere else on the field but inside the circles in front of the goal.

I'm not sure if that's different from other sports. And I probably could have described it better. Hope that helps.

From Wikipedia:

Short Corner

The short or penalty corner is a rather complicated set play that is awarded against a defending team when any offence is committed in the defensive circle, and may be awarded when a deliberate offence is committed in the defending 23 m area, or when the defending team deliberately plays the ball over the back line.

Short corners begin with five defenders (including the keeper) arranged along the backline. All other defenders must return to the centre line until the ball is in play. Attacking players begin the play standing outside the scoring circle, except for one attacker who starts the corner by playing the ball from a mark 10 m either side of the goal (the circle has a 14.63 m radius). This player puts the ball into play by pushing or hitting the ball to the other attackers outside the circle; the ball must pass outside the circle before the attackers attempt to get a shot or deflection into the goal. For safety reasons, the first shot of a penalty corner must not exceed 460mm high (the height of the "backboard" of the goal) at the point it crosses the goal line if it is hit.

Penalty Stroke

A penalty stroke (often referred to as a PS or just as a stroke) is awarded when defenders commit a deliberate foul in the circle which deprives an attacker of possession or the opportunity to play the ball, when any breach prevents a probable goal, or if defenders repeatedly "break" or start to run from the backline before a penalty corner has started. This penalty pits a single attacker against the goalkeeper, and is taken from a spot 6.4 m out and directly in front of the goal. The goalkeeper must stand with heels on the goal line, and cannot move his feet until the ball is played, whilst the striker must start behind the ball and within playing distance of it (in other words he must be able to touch the ball with his stick). On the umpire's whistle, the striker may push or flick the ball at the goal, which the goalkeeper attempts to save. The attacker is not permitted to take more than one shot, to fake or dummy the shot, or to move towards or interfere with the goalkeeper once the shot is taken. Hitting or dragging the ball is also forbidden. If the shot is saved, play is restarted with a 15 m hit to the defenders; if a goal is scored, play is restarted in the normal way. If the goalkeeper commits a foul which prevents a goal being scored, a penalty goal may be awarded, for other fouls by defenders, the result is normally that the stroke is retaken. If the taker or another attacker commits a foul, it is treated as if the stroke has been saved, and play recommences with a 15 m hit.

Hockey Penalty Corner