Help Nexus 6 question

[chrism9232]

I am looking to get a Nexus 6 to replace my galaxy s3. I am with sprint right now. I seen if i buy the phone from Google it will work with sprint and gsm. If i buy the phone from sprint is it the same phone can I switch to gsm later?

 

[chrism9232]

Is there any advanage from buying from google? I like the idea not being stuck with sprint.