lottery vs lucky dip

lottery and lucky dip both are nouns.

Word	Noun	Adjective	Verb	Adverb
lottery	Yes	No	No	No
lucky dip	Yes	No	No	No

As nouns, lucky dip is a hyponym of lottery; that is, lucky dip is a word with a more specific, narrower meaning than lottery:

lottery: players buy (or are given) chances and prizes are distributed by casting lots
lucky dip: a game in which prizes (e.g., candies or coins) are concealed in a container and for a small sum a player can draw one out at random

Other hyponyms of lottery include tombola, numbers, numbers game, numbers pool, numbers racket, raffle, sweepstakes.

lottery (noun)	lucky dip (noun)
players buy (or are given) chances and prizes are distributed by casting lots	a game in which prizes (e.g., candies or coins) are concealed in a container and for a small sum a player can draw one out at random
something that is regarded as a chance event	a selection or decision purely at random