Specifically say if we're designing OrderFood intent, IBM has an option to create an entity of type @sandwich and to which we can assign possible synonyms like (cheese steak, french dip, pastrami and what not).
Conversation service would return this entity @sandwich when the synonym is entered. Like when an user enters "french dip", it'll return @sandwich and not "french dip"
In Amazon, we've slot types but it returns "french dip" and not @sandwich. See https://console.bluemix.net/docs/services/conversation/entities.html#defining-entities for reference
According to your comment :
Not exactly. If the utterance is "Order me a french dip", I'm looking for {foodType:sandwich} instead of {foodType:french dip}. "French dip" is one of the synonym of sandwich and sandwich is the value of slot "foodType"
Possible solution is:
This will give value as sandwich. Hope it helps.