Head retention

I am currently drinking my first batch of beer. Its a hefeweizen. I didn't use quite enough malt so it turned out a little too light for my taste but other than that it is quite good. I bottled it maybe 3 weeks ago and the level of carbonation is very good right now. However I am having varying levels of head retention.

I poured a bottle into a regular pint glass and the bubbles in the head seemed a bit large. The head was foamy, not creamy and was gone very quickly. Last night I was in the process of moving so all my glassware was boxed away. I knew I would need some beer for this laborious task, so I grabbed a 16oz plastic clear cup from work before I left. In the plastic cup the head was very creamy and it lasted until the beer was gone, and since I was really busy it took me a good 35 minutes to drink. My question is why the huge difference in the head between the 2 cups?

Can the head differ from bottle to bottle? I know carbonating in the bottles isn't an exact science. Any tips on maximizing head retention?

it might be a soap residue on your glass

some soaps have a rinsing agent that affects head retention

heck, MOST soaps have a rinse agent (like Jet Dry) that'll kill your head retention.

your local bar/pub/tavern uses a special cleaner on all their glassware to avoid this. You can too, or you can use a saltwater solution to rinse your glasses after washing, which will remove the rinse agent and any soap residue.