What is the relation between gazebo and ignition library?

I know that my question sounds very generic. I'm new to gazebo and I'm using version 7.8. I have worked with some examples that use the transport layer to advertise a topic and publish Vector3 msg from the math library using Gazebo (only). Can I use instead Vector3 or the transport from ignition library and everything work as before? Is this still true if I want to use it with ROS? Hope that made clear what I ask. Ignition library looks very nice by the way :) Thanks!