According to Merriam-Webster, these terms are synonymous. Is there a legal difference between them?
For those in the profession: Is one preferred over another?
sigh Pulled it again!
Saying “I’m an attorney” is just the self-important way of saying “I’m a lawyer.” The terms are synonymous.
And to answer your second question, most in the profession prefer “attorney” because the word “lawyer” seems to carry more negative connotations.(Probably because of all of the Republican propaganda in recent years about evil “trial lawyers.”)
What’s the difference between a lawyer and an attorney?
Gypsy: Tom, I don’t get you.
Tom Servo: Nobody does. I’m the wind, baby.
We debated this issue, as well as the less than complete answer provided in the Mailbag column referenced above, at: What’s the difference between a lawyer and an attorney?
There is a definite difference between an attorney and a lawyer. An attorney represents people; a lawyer makes the law his business. Usually, those two things are done by the same people in this country; frankly, a paralegal is a lawyer, though we don’t usually let them so declaim, thanks to rules about being an attorney at law.
It sounds like the term “attorney at law” has been shortened to “attorney” in everyday speech. Legally, I could be made my mother’s “attorney” (i.e. power of attorney), even though I don’t have a law degree. Is this a correct assumption?
I’ve read the link. Where is the thread in which this topic was discussed?
You would be what is known as an “attorney-in-fact” for your mother, meaning that you would be authorized to conduct certain transactions on her behalf. The phrase “attorney in fact” is used to distinguish a person with this limited authority from an “attorney at law”. (And I would not go around referring to myself as my mother’s attorney in your circumstance. Instead, I would say “I have power of attorney for my mother.” Avoids confusion; keeps you from being arrested for practicing law without a license. ;))
Have to disagree with DSYoungEsq. Though he might argue for some historical distinction between “lawyer” and “attorney,” in common usage today, the two words are interchangeable.
In essence “attorney” is to “lawyer” as “physician” is to “doctor.” Same thing, fancier title.
Bonk Bonk, Spoke. Ya had me right to the last sentence. There are myriad Doctor’s that are NOT Physicians, but a Physician has to be a Dr. to be a Physician. To wit: A PhD, a DD ( Doctor of Divinity ). Just to name two.
Cartooniverse
If you want to kiss the sky, you’d better learn how to kneel.
Conceded. But I was speaking of the common parlance. When the average Joe says “I need a doctor!” it’s a pretty sure thing that he’s not seeking out a Doctor of Philosophy. Heck, for that matter, lawyers are “doctors” too (Juris Doctor).
Sorry, spoke, but just because unwashed plebians use terms interchangeably incorrectly doesn’t make them truly interchangeable. Kinda like watching everyone use less when they mean fewer.
And if you think it doesn’t make a difference, trust me, it does. I am sitting here in Ohio awaiting the ability to be an attorney, though I remain a lawyer.
I cast my lot with the “unwashed plebians” over at Merriam-Webster. You want to create your own special meanings for words, go ahead. 
Oh, and by the way: Try putting out a shingle using the word “Lawyer” when you have not been admitted to practice. I’m betting the state bar (and for that matter, the local constabulary) will agree with my definition.