Twins aren't truly identical. Take Jacob and Isaac Clark, for example. Sure they look alike, but when it comes to the track, Jacob relies on endurance and stamina. He's a mile guy. Isaac has more speed. He can blaze around the track in the 400m dash.

But on Thursday at the Marine Corps Holiday Classic it will be hard to see who has the edge, as the Pleasantville, N.J., natives square off in the 800, the 'tween test of the teens. At the Loughlin Games, Jacob won the 1,000m run in meet-record time (2:27.71) while Isaac was third in a hotly contested 600 (1:21.19).

Phil Anastasia of the Philadelphia Inquirer talked to the two about the 800 over the summer.

"The 800 is my favorite race," Jacob told him. "I like the 1,600, but in the 800 you have to use your speed and know when to make your move."

Isaac pointed at his brother and said, "I like the 800 because I get to run with him. We're luckier than a lot of other runners because we have each other. It makes you go faster."

Along with the Clark twins, there will likely be a lot of new holiday shoes on display as teams from up and down the Eastern Seaboard converge at the Marine Corps Classic, just two days after Christmas.

Right off the bat — the first two running events at 9 am — will be something new. It will be the first in a season series of the one-mile steeplechase. The boys' chase will be followed by the girls before the relays begin.

Both 4x800m and 4x200m events take the schedule to nearly 1 pm, when the opening ceremonies take place, followed by the elite 800-meter runs. New Haven Hillhouse High All-American Precious Holmes is schedule in the girls' race, giving both genders impressive early-season firepower in the event.

From there the schedule leaps back into relays, including the 4x200m finals and high-powered invitationals for both genders in the distance medley relays.

The last of the field events begin at 2 pm while the final running events of the day — the varsity 4x400m relays — will conclude before 8 pm.