MassTransit vs NServiceBus: What are the differences?

Developers describe MassTransit as "Lightweight message bus for creating distributed applications". MassTransit is free software/open-source .NET-based Enterprise Service Bus software that helps Microsoft developers route messages over MSMQ, RabbitMQ, TIBCO and ActiveMQ service busses, with native support for MSMQ and RabbitMQ. On the other hand, NServiceBus is detailed as "*Enterprise-grade scalability and reliability for your workflows and integrations *". Performance, scalability, pub/sub, reliable integration, workflow orchestration, and everything else you could possibly want in a service bus.

MassTransit and NServiceBus can be categorized as "Message Queue" tools.