There sure is a difference. I learned from trial and error about Publishing.  The difference is a Press Company meaning you pay out of your pocket for their services. Majority of these Press Publishing company don't state that they are Press because they want money, money, and more of your money.  Press companies have a mass array of package deals that are awesome but the catch is: outrageous prices with no significant  guaranteed you'll get what you've paid for. 

Then there's a Publication house where you try to hire a Literary Agent, a Manager or a Attorney in your genre. Seeking one of these three Professions isn't easy.  An Agent requires a Query letter in precise details detailing certain descriptions of your book and your writing styles. You are selling yourself to them in order to get represented by one of them. If your book gets the green light then the Agent, Manager or Attorney will do the leg work for you by representing you and your book. So the difference is a Publication House pays you for your book and a Press Company you pay out of your pocket for their services.