Revelation 22:12 says,
“Behold, I am coming soon! My reward is with me, and I will give to everyone according to what he has done."This indicates that Jesus will reward each person differently. This is not a matter of salvation (every believer receives this), but it shows us that there will be a time that all will essentially reap what they sow. Exactly what those rewards are are unknown.
And so although all Christians are granted eternity in heaven, not all Christians are the same in a sense that some simply believe, but others believe and DO!
For more information, please read this blog post: http://www.gotquestions.org/levels-heaven.html
[answered by Pastor KJT]