These two practices are very similar at first glance, but the differences between these two practices has to do with how you go about interacting with the astral plane of existence. This will not be a super expensive look, but will provide some Basics on the differences.
Astral projection is the act of literally projecting your astral body from your physical body, and is a way to explore the astral by using your body that already exists on that plane of existence. When you are astral projecting you are actually there in the astral plane.
Astral travel is the act of sending out a thought form construct that will be able to carry your consciousness on to the astral plane of existence, so that you can explore it without using your astral body. when you are astral traveling you are viewing the astral plane with your consciousness.
Astral travel is said to be a lot easier then astral projection, because it takes less effort to view with your consciousness, then the amount of energy it takes to separate your astral body from your physical body. Astral projection is also said to be more dangerous primarily, because you are using your astral body which will be able to interact with other energy constructs, that may not always be good for it. Astral projection is also said to be very Vivid, because of the connection you have to your astral body, where you are actually presently their experienceing it, much like you do in your daily life with the physical plane. Astral travel is a lot less vivid, because you are very close to that plane of existence, but are sort of peering through at it instead of actually being there.
These are just some of the differences between these two practices, and by learning more about each one you will be able to uncover more differences. Which will allow you to more effectively choose, which one of these will be better for you in your interaction with the astral plane.