In queue, you only have one receiver or consumer; unlike in topic where in you can have your message be disseminated to a number of subscribers. Also, in topic, the publisher has to be continuously active for a subscriber to receive the messages. Otherwise the message will be reallocated. 

http://www.differencebetween.net/technology/internet/difference-between-queue-and-topic/#:~:text=In%20queue%2C%20you%20only%20have,the%20message%20will%20be%20reallocated.