Cigarettes are the Enemy

Hi, My name is Debi, I'm 52 years old. I recently received the results of my sleep study.  I slept well for about 5 hours, but apparently wasn't doing well for the first several minutes prior to that, my oxygen level was low, so was given oxygen for the remainder of the test.  My doctor received the results and tells me that I do not have obstructive sleep apnea (which I was diagnosed with 8 years ago, but never treated) but that I instead have COPD.  I have cut down from 2-2 1/2 packs to 12 cigarettes a day and am now awaiting the oxygen to be delivered that I will use during my hours of sleep only.  I am a little concerned however because I'm not sure my doctor knows how short of breath I am the rest of the time.  I soooo do not want to be that woman who pushes around an oxygen tank wherever I go.  I have a return visit with my doctor in 6 weeks.  In the meantime I have questions that I didn't ask when he told me the diagnosis, it was just overwhelming.  The biggest thing I'm wondering about is if a sleep study alone can diagnose COPD. The only other test I've had was before the sleep test, they had me blow into one of those things that tells your oxygen (intake or output?) From what I've read I also have the symptoms of congestive heart failure. So can someone please tell me if the pulmonologist who read the sleep study can tell for certain that it's COPD and not heart failure or something else?   I am also confused as to what the difference is, if any, between Emphesema & COPD.  My MD used both terms.  Thank You Very Much,    debi