my knowledge of crown green bowls is limited but slightly better with lawn green bowls so to answer your questions
Crown Green Bowls is played on a green you could describe as the small square type speed hump with a rounded Top/Crown and if stood atop this Crown in the middle the sides fall away to a surrounding ditch ,, the jack ball used is biased and is larger than that used in lawn Bowls and can be rolled up in any direction on the green ,, the initial start of the game is started with a toss of a coin to determine who places the circular rubber mat/disc and it is he/she who determines the jack direction/length to be played the player with the nearest bow/sl to the Jack wins that end
Lawn Green Bowls is played on a flat level green in lanes/rinks from end to end again the start of the game is determined by the toss of the coin the winner usually laying a rectangular mat to roll up the jack to set the distance again the nearest bowl/s deemed closest to the jack score and the player/team takes control of the jack for the return end ,, there is a minimum/maximum length for the jack to achieve and can come to rest between these two points ,, the jack is always placed on the centre line at the point where the jack comes to rest, the game can be played in the following formats with the amount of bowls per player Singles 4 each Pairs 4 each Triples 3 bowls each Foursomes 2 bowls each hence the reason lawn bowls are usually sold in sets of 4 it should be noted the Jack ball used in lawn green Bowls is Bias Free and must conform to Diameters and Weights within the rules of the game
Crown Green bowls are generally lighter than Lawn Bowls and usually sold in pairs and may have a different bias to lawn bowls Not sure if Crown Green bowls is an International Sport or just confined to the North West and the Midlands Areas here in the UK ,, Contrary to belief there is no lump of metal in the bowl to create the Bias it is achieved by the centre line being offset to one side normally indicated by a smaller circle on one side of the Bowl this is the direction the Bowl will Curve towards the Jack ,,
Lawn Bowls is an international sport and has a governing body the Bowls used have to be date stamped and be current to enable their use in County National and International games
Date Stamps ,, a disused date stamp is the BIBC this has been replaced by the WBB date stamp if the Bowl has an out of date stamp it can usually be used at club level and some local league games for example if you have stamped on your bowls BIBC 01 or WBB 01 these could be used even at local level even though they are out of date so should you buy a new set of bowls lets say last year the date Stamp would be WBB 22 meaning they are valid till 2022 (10 years),, Older sets of Bowls can be tested and re-stamped if they meet the criteria laid down regarding weight Circumference and the results from the test table where the bowl must achieve the set mark again this Stamp is valid for 10 years which is then etched onto the bowls and a certificate issued .. I would suggest a web search for Official Testing Centres nearest your location (Pershore Bowls is the nearest to me) ,, Manufacturers have different models of Bowl available each with different Biases some Have very narrow Curves usually suited for indoor use and very fast outdoor greens and others with a Mid to Very wide draw usually suited for outdoor greens ,, Bowls also come in varying sizes to suit the size of the players hand or what ever size suits the player ,,
Some Manufacturers produce both Lawn and Crown Green Bowls
Crown Green Bowls are made by Stevens ,, Taylor ,, Drakes Pride ,, to name 3 ,, Lawn Green Bowls are made by Henselite ,, Allmark ,, Greenmaster ,, Taylor ,, Drakes Pride to name a few
I hope this has helped to answer all your questions regarding both forms of the game