Lynch's ad is a bio spot that introduces the congressman to Massachusetts voters, while Markey's focuses on his work on gun-control measures.
The focus of each ad echoes what the candidates have, so far, made the focus of their campaigns: Lynch has touted his personal narrative during his campaign, while Markey has framed himself as the most liberal candidate vying for the nomination.
Markey's ad touts his work on a ban on Chinese assault weapons in 1994, "long before tragedy swept our nation," as the narrator says, and adds that he's "joined President Obama fighting for tougher gun laws to make our communities safe."
"I'm Ed Markey. In the Senate, I'll keep standing up to the gun lobby. I want these guns off our streets. That's why I approve this message," Markey says at the end of the ad.
Massachusetts has some of the toughest gun control laws in the nation, and following the massacre in Newtown, Conn., Democrats in the state legislature expressed support for expanding those measures.
While Lynch opposed an expanded assault weapons ban during his time in the Massachusetts Senate, a measure that ultimately passed, during his tenure in Congress, Lynch has supported gun-control.
Both Lynch and Markey have received F grades from the Massachusetts pro-gun-rights group Gun Owner's Action League.
Lynch's ad features shots of the congressman walking through a factory and speaking with what look to be advisers. In a voiceover, Lynch shares his background — "I grew up in public housing. Mom was a postal clerk. Dad was an ironworker." — and mentions his own time as an ironworker, as well as his tenure in Congress.
"In Congress, I've learned that doing what's right means knowing when to compromise and when to stand firm," he says, closing with an approval of the ad "because I believe every working family deserves someone fighting for them."
The ad hits on all the rationale Lynch has given thus far for his run. He has noted previously that his background as a union worker would make him unique in the Senate, and has, in public appearances and to reporters, pressed his humble beginnings as reason he can relate to voters.
And it notes that Lynch was an ironworker for "18 years," possibly a subtle reference to critics' assertions that his Democratic primary opponent, Rep. Edward Markey, who has served in Congress for more than 30 years, has spent too much time in Washington.
But Markey also touts his own upbringing as part of his appeal. His father worked as a milkman, while his mother took care of him and his brothers, and Markey ultimately worked his way through college.
Markey remains the front-runner in the race, leading in polls and in money in his campaign coffers, at last count.
But Lynch's ad is an effort to get out ahead in introducing himself to voters, before Markey can brand him with his more conservative positions on issues ranging from abortion, which he opposes, to President Obama's health care law, which he voted against.
The two lawmakers served in Congress together for over a decade and have both said they have a good working relationship, and thus far, the primary has not become confrontational.
But with six debates planned before the April 30 primary, the current comity could give way to a more combative strategy from both lawmakers as they vie for the nomination.
Republicans have three contenders battling for the party's nomination, but Democrats are heavily favored to keep Secretary of State John Kerry's (D) seat when the general election rolls around on June 30.
Watch Markey's ad: