Difference between Pending Messages and Enqueue Counter in Active MQ?

pending messages = number of messages CURRENTLY waiting for delivery in the destination (the current size of the queue)

enqueued messages = number of messages that where enqueued in the destination since the last statistic reset. This number can only rise.

dequeued messages = messages delivered from the destination to consumers. this number can be higher that the number of enqueued messages if a message was delivered to multiple consumers (topics).

Messages Enqueued = Number of messages sent to the queue since the server start

Messages Dequeued = Number of messages received+deleted since the server start