Are there different harbor front tour companies?
Not sure what you mean by "harbor front trips" but if you mean the boat tours of the harbor from Nyhavn and other docs, yes. The Rick Steves Copenhagen guide book explains the Nyhavn boat tours. We took Rick's advice on saving money and walked the extra 50 meters and took the cheaper boat tour.
The cheap option for a harbour trip is Netto-bådene: http://www.havnerundfart.dk/
Yes, we walked the 50 meters and took the Netto tour. Rick says same route just cheaper. The one difference we experienced was returning to the Nyhavn dock during a very high tide. The Netto boat could not get under the bridge over the harbor while its pricier competitor's boat could. The Netto boat had to back up and drop us off at the end of the Nyhavn near the 71 Nyhavn Hotel. We got to walk the extra 250 or 300 meters to the head of the Nyhaven.
PS Washrooms (gratis and clean) at the head of the harbor. No washrooms on-board.
Thank you that is very helpful