After reading a number of articles we gained some perspective of what was meant by these terms.
When communicating the Big Gospel, focus would be on... bigger elements. This isn't meant to convey a value judgement between big and small, but to help describe the idea. The big Gospel points the individual to the larger community and the larger mission. It emphasizes the individual's role in God's big plan. It sees things from a cosmic perspective. These aspects are positive but they contain drawbacks. Sometimes this expression can leave people feeling lost or out of touch with God. It can lack personal conviction. (As Luke said in a moment of discovery, it's "not as sword attacking." Oh Luke). There is a danger here to turn everything into the Gospel. There is a danger to lose the core of Christ's payment of our individual debt on the cross.
In contrast, a small Gospel connects with the individual's need for salvation and forgiveness through Christ's sacrifice on the cross. It's clear and straightforward. It is bold and requires a personal response. It calls for a personal relationship with Christ more intimate than any that can be experienced otherwise. This approach has its weaknesses as well. It can be easy to lose sight of our role as stewards here on earth when we see our faith as simply individualistic. It can lack a view of our role in God's story and His kingdom. Sadly, it can sometimes become irrelevant.
I hope this has spurred questions in your mind as it has mine. I have taken a new look at my ministry to evaluate how well I synthesize these two approaches to God's work in our lives and in this world. It's an encouragement for some of what I'm already doing as well as a challenge for changes that can be made.