What is the difference between a Trademark and a Service mark?
A trademark can be any symbol, phrase, design, word, or combination of these things that identify your GOODS, essentially they are a source identifier.
A service mark is also a source identifier that can be a name, logo, device or any combination of those things that identify a SERVICE.
Often “trademark” is used as a blanket identifier of services as well.
Examples of trademarks:
McDonalds golden arches
Coca Cola bottle
Twitter (downloadable software, etc)
Examples of service marks:
FedEx (the service of shipping & delivery of goods)
Google (the service of being a search engine)
Twitter (services: advertising and marketing, networking, promotional, etc)
Twitter is a great example of how you can have a mark function as both a trademark (goods) and service mark (services). Check out their registration for more information. Twitter USPTO Registration