These are all separately registered items with different agencies, yet they all fall under TRADEMARK law and thus potential infringement must be considered before choosing or registering a name. Registration of a name or mark with a state or federal agency does not guaranty that you are not infringing upon another's prior use of a similar name or mark. Those agencies are only adminsitering or regulating the use of that name for administrative purposes within the confimes of their particular purpose.

Any words, symbols, or logos used in connection with goods or services in commerce are automatically common law "trademarks".

Legally, Trade Marks are used in connection with goods (ex: "Nike" for footwear) and Service Marks are used in connection with services (ex: "Merrill Lynch" for financial advisers), however both are commonly lumped together and referred to as "trademarks".

You acquire common law protection of a mark upon its FIRST USE in commerce under the laws of a single particular State in the U.S. This kind of commerce is known as INTRASTATE COMMERCE. Every State also mainatains a registration system for trademarks used within the confines of that state, which provides the owner with added protections and benefits, and varies by law from state-to-state.

Use of a mark in commerce in more than one state (crossing state lines) is known as INTERSTATE COMMERCE which is regulated by the federal government and its laws, and qualifies an owner to register the mark for FEDERAL trademark protection with the United States Patent & Trademark Office (USPTO). Once again, registartion provides added protection and benefits.

Different States call it different things; in Maryland it is called a Trade Name, some states also call it a Fictitious Name, and yet others, an Assumed Name. Regardless, if you are trading or doing business as something other than your legal name, then by the laws of every State in the U.S., you are required to register that name so that you put the world on notice as to who that business legally is. The owner could be an individual or a corporate entity, but so long as it is doing business as something other than its legal name, it is using a trade name. This is mainly for public policy reasons in order to protect an individual who might be injured by that "business" so that they can find the legal owner and pursue them in a legal capacity.

A Trade Name becomes a common law trademark or servicemark upon its first use in commerce in connection with any goods or services. Therefore your chosen trade name could infringe upon another's trademark.

"Blah Blah Blah, Inc" -or- "So-And-So, LLC" may be the name of your legal entity, but when used in commerce in connection with goods or services, you have entered the realm of trademarks. Worse yet, some states such as Maryland, even permit multiple registrations of the identical name so long as the entity type designator is different (INC vs LLC vs LTD vs INCORPORATED, etc) and they advise you "buyer beware" as to trademark implications, providing you with no promise of protection relating to trademarks.

Before choosing a name to use for your business or legal entity you must consider whether the name will infringe upon a prior user's mark anywhere, and perform an adequate and comprehensive trademark search. Attorneys perform this service, and good attorneys should provide "basic" searches and advice as part of their incorporation services.

EXAMPLE:
Let's make pretend that I own a corporation registered as "Diane's Foods, Inc." I register a trade name for this corporation to trade or do business as "Pizza In A Jiffy" and have a logo designed of a pizza with the letters P and J in the middle of the pizza. I register another trade name as "Burger In A Jiffy" and start building my Diane's Foods empire. I start selling T-shirts at both businesses with "Diane's Foods" on it, as well as the name of each business.

Diane's Foods is a trademark, as well as Pizza In A Jiffy and Burger In A Jiffy. So I should also register a state trade name for "Diane's Foods" (without the "Inc").
Upon its first use in commerce anywhere (in a particular state, say Maryland) I file to register a STATE trademark for each. IF and when I start using the names in more than one state, then I file to register a FEDERAL trademark for each. In fact, prior to its USE in commerce across state lines, I could also file a federal INTENT-TO-USE which is a "placeholder' of sorts and puts the world on notice that I'm holding this name to register it upon establishing interstate commerce. And let's not forget the logo for the pizza business, which also qualifies to be registered separately as both a STATE and a FEDRAL mark too.