There is a difference. There is the indwelling Spirit in the beleiver, and then there is the baptism of power of the Holy Spirit that comes from the outside. I've experienced it, and even literally SEEN it for myself. Most in the church today know all about the head knowledge of having the Holy Spirit in them in salvation. But very, very few in the church know about the 'falling' of the Holy Spirit in power. They are quite different. But, if just the falling of the Spirit makes you a 'different', new person, how much more the Spirit within a man who never leaves? Think about it. The point is, the agent of change in a person that makes them 'new' is the presence of the Holy Spirit. A Spirit that can just as easily depart from a person's body as he came.
The problem is, most people in the church today think about the born again experience as a new child being brought into the world. No. What it is like is when God breathed breath into Adam and he became a living soul. Or like when a baby takes his first breath and he becomes a living soul, new in existence. In the same way God breathes a NEW spirit into our bodies and so we are 'born' that way. But when you talk to Christians they seem to think a new baby gets birthed into existence when you get born again. It's really quite silly. No. Born again means being born fresh and anew. A new Spirit is inside of you that makes you 'different'. The same you, just different now.