T6 front springs - difference between 2grey/1Green and 3grey/1green

[M&J]

Folk, apologies I am new to this forum but am looking for some help. Could someone please advise what the difference is between the 2 types of spring as I may have the option to purchase a pair of 3grey/1green springs as I have broken one of my original 2gray/1green. Any help would be appreciated. My van is a 2018 4 Motion T6 204