A change of surface can make a familiar delivery feel unfamiliar. There is no universal claim that every synthetic green is faster or every natural green is slower; the individual rink and conditions matter.
Both surfaces can be lawful
World Bowls law 46.4 permits a vegetation playing surface or a synthetic surface approved by a member national authority. Event conditions and venue rules still govern the match, so check before changing equipment or practice plans.
Test pace before changing technique
Use trial ends, when permitted, to deliver a draw on each hand and note where the bowl stops. Adjust weight in small increments. A change in grass moisture, temperature or synthetic pile can matter more than the category name.
Watch the line and finish
Observe the bowl’s turning point and final metre rather than assuming the same aiming point will work. A side that feels open on one surface may finish differently on another. Share observations with teammates in concrete terms.
Bring a simple comparison routine
Keep your stance and release steady for a few bowls; vary only the target and delivery weight. Record the two most reliable hands and revisit them after weather or traffic changes the rink.
Source: World Bowls Laws of the Sport, law 46, and Bowls Australia coaching activities. Check your national regulations and event conditions before a competitive game.
Read the actual rink in front of you; the surface label is only a starting clue.
For a shared view of close heads, try WGTS for iPhone or WGTS for Android. Use the official measuring procedure whenever your competition requires it.