OK I realize when you read this many will be thinking they really understand the difference. When I was in church I heard this comparison many times. Even the fundy bumpersticker: "I'm not religious, I just love the Lord." plays to the comparison. Many churches, especially charismatic/non-denominational Evangelical churches have a lot of "pride" in their "anti-religious" stance. Even I will not claim to be an expert because I recognize I have to fight being dogmatic about my anti-religion, anti-church rhetoric.
All that being said, the difference doesn't come down to what you think you are. Many religious people espouse anti-religious sentiments while exhibiting Phariseeical traits and beliefs.
Spirituality comes down to self-reflection. It comes down to looking not just at what other people do, but what you do. Spirituality is living the beliefs others espouse, not necessarily because you "believe" them, but because they are just who you are, the way you live your life.
Perhaps the biggest difference is spirituality is totally NOT contingent on anyone else; not their beliefs, not their thoughts or feelings, not their approval or acknowledgement, not even neccessarily their knowledge. I am not one of these people who believes if you dod a good deed you should never mention it. I think there is a difference in talking about who you are and bragging. I don't think you should seek out opportunities to tell your good deeds, but if someone asks you or if it comes up, it is not a bad thing to acknowledge-but recognizing you are not doing it for that acknowledgement.
Perhaps it is that recognition that makes the difference. It is self-reflection that makes that recognition possible. It is critically important that you live the EXAMINED life. It is the only life worth living. Examine WHY you believe what you believe and do it HONESTLY. Examine WHY you do what you do and look at it HONESTLY.
If you go to church for the social aspect-just admit that. There should be nothing wrong, social interactions ARE important and a reason we go to church, temple, mosque, etc.
If you are a smart person just admit that, don't buy into the lie our society has created that being smart means being arrogant. If you are arrogant, work on that (I have to) but that doesn't mean you shouldn't ackowledge your intelligence.
WHY do I say all this in this post? Because it is those first steps of honesty that create a habit of honest self-reflection. And it is that honest self-reflection that can lead to real good being done, real love being shown, real spirituality and not religiosity. And with real spirituality built on honest self-reflection, goodness and love-we can truly change the world.
That was what Jesus and Buddha were really aiming for-stripping the religions away from their core message and purpose and changing the world. Think about it and . . . ACT.