BV vs yeast infection

I have a yeast infection that is probably the worst one I've ever had. 2 days ago I got the over the counter stuff, didn't touch the yeast infection. 
I got the treatment again today, but before I did I called my doctor before they closed and told him I might need the pill that treats yeast. He told me to go ahead and use the over the counter treatment and if it doesn't work to come in next week so he can find out if it's yeast or bacterial vaginosis? 
What's the difference between BV and yeast? How does the treatment for it differ? I didn't ask him, I didn't think to ask him. And I can't ask him until Monday so might as well ask here.