There are a few BIG differences ... 

1) Satellite companies will always be plagued by SLOW response times from the internet. (This is called latency) Even with a 12meg download speed you are still going to have to sit and wait on that lag. Typical satellite response is 800-1200milliseconds. Air Link response times are typically less that 50milliseconds. 

2) Satellite providers cap their usage. Air Link does not.