In both instances, the phrases are exactly the same in Koine. On their face, they refer to a locus in or among the Spirit. In the way that one can be "in the wind" or even "in the sun", the Apostle John was in the Spirit. What he is communicating by this was that he was experiencing a pointed (and I would say virtually tangible) consciousness of the divine presence.
This was not John's common or moment-to-moment experience of the Spirit. There are clear enough references to the inception of the experience in both occurrences. In the first usage, this something special happened to occur one Sunday on Patmos. In the second usage, the condition was initiated immediately upon hearing the voice beckoning him to heaven. In both cases, it seems clear that the experience as recorded represented a change from what was going on before.
The word used [ginomai] to describe the existence of John's state packs within it the idea of "becoming" rather than simply being. In other words, John emerged into this state (really, was born into it) at the moment in reference. It is not described in trance-like terms, though the word "ecstasy" is often bandied about while commenting on it. It is ridiculous to do so in my mind, for John betrays no rapture, no enthusiasm, no exhilaration nor any euphoria in conjunction with this experience. Really, there is nothing but matter-of-fact reportage associated with it.
More than anything else the state of being in the Spirit, at least from the accounts of John's being so, is about awareness of the very presence of God--not theoretically, not by faith, but in actuality. If we can generalize from John's experience to any of our's (and I think we can), being in the Spirit is like having a light go on in the dark which suddenly reveals things one would otherwise be unaware of. Those things could be revelations regarding heaven or earth or about the activity of God in a moment past, present or future.
If there is anything precedential or paradigmatic about John's experience, I think it can be said in regard to its application to us, that coming to be in the Spirit (really, acting on charismatic distinctives) is about coming to an acute awareness of God's immediate presence and what he is up to. As a result of that awareness prophecy, or healings, or works of power, or miracles are then manifested in this world. Those manifestations do not break into existence because someone exercised enough faith to produce them, but because someone had come to be in the Holy Spirit.