In matchplay, the difference between two players' handicaps is the number of strokes given by one player to another. These strokes are taken at different holes according to the Stroke Index or Rating of each hole on the course.
If Player B is to receiving 5 strokes then the player takes one shot off the actual score at each of the holes with Stroke Index 1-5. This gives a nett score for each hole and this is the score used to calculate the result of each hole.
If a player is receiving more than 18 strokes, say 20, then the player receives one stroke at holes with Stroke Index 1 to 18 and a second stroke at holes with Stroke Index 1 and 2.
The number of shots given or received depends on the format of matchplay:
Singles
Lowest handicap player gives strokes to the other based on the full difference between the two handicaps.
Foursomes
Each pair adds up their handicaps and you work out the difference between the two totals. Divide this difference by two to get the number of shots the higher handicap pair receives from the lower handicap pair. Also known as "half the difference of the combined".
Four Ball Better Ball
The lowest handicap player gives strokes to the other three players based on three quarters of the difference between the lowest handicap and that of each player.
Greensomes
Calculate the handicap for each pair as follows: (Lower handicap x 0.6) + (higher handicap x 0.4). If the handicaps in the pair are equal, then use half the combined handicaps. The lower handicap pair then give strokes to the other based on the full difference between the two handicaps.
Extra Hole Playoffs
If a match finishes all square and goes into extra holes, then strokes continue to be taken according to the Stroke Index of the course.