Both names are comprised of fifteen letters
Coincidence? None of their first, middle, or last names have the same number of letters. And why should it be significant that both assassins had the same number of letters in their full names when the same wasn't true of Abraham Lincoln and John Fitzgerald Kennedy, or of Andrew Johnson and Lyndon Baines Johnson?
Once again, perhaps we should focus on the substantive differences between the two men: Booth was born into a prominent family and, like his father, was a well-known, popular, gregarious actor. Oswald was born (and lived most of his life) in near poverty-level circumstances, never knew his father (who died two months before Oswald was born) and was an obscure, moody malcontent who never had any close friends or a steady job. Oswald was married with two children; Booth had neither wife nor offspring. Oswald enlisted in the Marines, but Booth kept a promise to his mother not to join the Confederate army.
Booth ran from the theater and was caught in a warehouse.
Oswald ran from a warehouse and was caught in a theater.
Another "coincidence" that is both inaccurate and superficial.
Booth shot Lincoln in a theatre of the type where live stage shows are held, then fled across state lines before being trapped and killed in a tobacco shed several days later.
Oswald shot Kennedy from (not in) a textbook warehouse, then remained in Dallas and was caught and taken alive in a movie theater a little over an hour later.
Booth and Oswald were assassinated before their trials.
Another superficial similarity with much more significant underlying differences, and a potentially dubious use of the word "assassinated."
After Booth shot Lincoln, he fled the scene and eventually (with co-conspirator, David Herold) crossed the Potomac from Maryland into Virginia, eluding capture for a total of eleven days before federal troops finally discovered him to be hiding on a farm belonging to Richard Garrett and surrounded the barn in which he and Herold were sleeping. The two men were ordered to surrender: Herold complied, but when Booth failed to drop his weapon and come out, the barn was set ablaze. A trooper named Boston Corbett, who was watching Booth through a gap in the barn's siding, shot the assassin. Whether Corbett can be said to have "assassinated" Booth is problematic -- the deeply religious Corbett sometimes claimed that he had shot Booth because "Providence directed" him to do it or because he "did not want Booth to be roasted alive," but he also testified that he shot Booth because he "saw [booth] in the act of stooping or springing and concluded he was going to use his weapons."
Oswald left the warehouse from which he shot Kennedy and was arrested in a movie theater a little over an hour later by police officers who had no idea who he was. (Oswald was initially arrested only for the murder of Dallas police officer J.D. Tippit, whom he shot while in flight; his connection to the Kennedy assassination was not established until later.) Oswald was captured alive and remained in custody for two days before being gunned down by Jack Ruby, a private citizen.
Other differences: Booth was shot in the back in the neck and lived for another three hours; Oswald was shot in the abdomen and died within minutes of his arrival at Parkland Hospital.