I searched this forum about EAD and AP, and now I have a question about "Use EAD". Suppose I had H1B, and I applied for EAD and AP. I went back to China and used AP to come back to the U.S. Is my H1B still valid? I applied EAD, but never used it. What is the difference between "apply for an EAD" and "use an EAD". Thanks.