Hi Naz 089,
It could be that because the grass is slightly thicker on your practice ground the ball sits up a little better than it would do on a fairway on the course. If you are practcing a lot from this sort of lie then you will become used to hitting the ball slightly higher up off the ground. This will not help you when you are hitting off a tight fairway lie on the course as you will likely hit halfway up the ball or above resulting in a topped or thinned shot.
Try practicing off a slightly tighter lie (shorter grass) and you will notice the differenec on the course. Basically you have become used to hitiing the ball off longer grass.
Good Luck & let me know how you get on...
