mysecretname; Hypomania for me can present as irritability, impatient etc. It can also present as me being super duper happy, driven etc. It really depends, but unfortunately we have no control on how it presents.
Hypomania and Mania share symptoms. Where the "line is drawn" between the 2 is severity. The only symptom that isn't shared is hallucinations and delusions which is a symptom only listed for mania.
I have attached a link to the Mood Disorder Society of Canada website. There is a booklet on BP that can downloaded for free. It does a good job of giving a general overview of BP and also defines hypomania and mania.
http://www.mooddisorderscanada.ca/page/quick-facts
The book in my signature was written for spouses, family members etc. and I can highly recommend that. I hope that helps.