The difference between the rapture and the Second Coming is as follows : Matthew 24:31 states, "they shall GATHER TOGETHER His elect" whereas Revelation 19:14 states that "His elect" are following Him,  "The armies which were in heaven followed Him on white horses. “ The reason that they , His elect armies,  "were in heaven" as stated in Revelation 19:14 is because they were previously raptured to heaven as stated in Matthew 24:31.

According to Your Holy Word,  come Lord Jesus !