noun
BAD : Why didn't you invite me to your marriage?
GOOD : Why didn't you invite me to your wedding?
BAD : I have just received your marriage invitation.
GOOD : I have just received your wedding invitation.
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marriage = the ceremony of becoming husband and wife considered from a purely religious or legal point of view: 'Her parents are against the marriage.'
wedding = the occasion when this ceremony takes place and the celebrations that follow it: 'I never see most of my relatives apart from at weddings.'