If in case you would like to know what these two terms are, these are normally used for gaming. People who would like to have a more PVE gaming may choose gnomish engineering. This is because of the higher level of utility that will be available throughout the game.
Another reason why people would choose this is they will get gnomish battle chicken which can be used when doing battles to win. Take note that people will only have this option when they already reach level 200 in engineering before that. People can still choose to get goblin engineering if they want to try out a different location and if they want to see other trinkets.