Mario is the protagonist of the Mario series itself. Mario is an Italian plumber that lives in the Mushroom Kingdom and his main duty is to rescue Princess Peach from the Koopa tyrant, Bowser. Mario has by far more appearances in the series itself and due to appearing in so many games throughout the years, he has become a video game icon even earning nicknames such as The Face of Nintendo and Mr. Video Game Himself. Mario is often the main and only playable protagonist in the earlier games but, as of recent games lately, Mario is playable along others. In the sports spin-off games, Mario tends to have average status which dates back to his role from Super Mario Bros. 2.
Even being a well-known hero, there are other games in the Mario series where Mario either has a side role, makes a cameo, or doesn't even appear in at all. This is the most cases for the Donkey Kong, Yoshi, and Wario series. Mario is often "player 1" in most of the earlier video games with his brother Luigi being "player 2". Mario is well known for his jumping ability where, back in the original Donkey Kong arcade, he was known as Jumpman. However, even though Mario is well known for his jumping skills, Luigi is superior in the technique as shown in games such as Super Mario Bros. 2 and Super Paper Mario.
Luigi is the deuteragonist of the Mario series. He is the younger brother of Mario and is well known for being tall and wearing green. Luigi made his debut in Mario Bros. as player 2 and has been commonly portrayed as player 2 in other games like Wrecking Crew, Super Mario Bros. and Super Mario World. However, it was until Super Mario Bros. 2 where Luigi was given a role that made him different such has his flutter jump and his slippery walking. Luigi is often in Mario's shadow as his older brother is always saving the day from Bowser. However, it was until Mario is Missing where Luigi was giving his first stand-alone role that actually involved rescuing Mario.
Much later in the series, Luigi's role in the series was quickly starting to rise. Luigi's second stand-alone game, Luigi's Mansion, involved him exploring a haunted mansion armed with a ghost-capturing vacuum known as the Poltergust 3000. His role in the game was similar to his last one as he must rescue Mario again. Luigi also teamed up with Mario in the Mario & Luigi series where he is often the comic relief character. In the sports games, Luigi's stats are often similar to Mario in the average class. Luigi is often known to jump higher than Mario but run a little slower than him.