While Luke is portrayed as older than Ravi (the former being born in August 1999 and the latter in March 2001), Cameron Boyce is actually four months younger than Karan Brar (May 1999 and January 1999 respectively).
Jessie takes place in the universe as "Good Luck Charlie," "Austin & Ally," "Shake it Up," "Liv & Maddie," "Best Friends Whenever," "Girl Meets World", "I didn't do it", and "that's so Raven" Because Hannah Montana and Wizards of Waverly Place crossed over with The Suite Life, and Mr. Moseby made a cameo on Jessie, and Raven goes to the Tipton hotel in season 4 of "that's so Raven" so it would make logical sense that those two shows are also in the same universe as Jessie.
Jessie was so popular that Disney rewarded it with a spin-off. However, in the spin-off, Cameron Boyce (Luke) doesn't star it it, due to him starring in Disney XD's "Gamers guide to pretty much everything", and there is a rule that "if you want to star in a new show, you cannot continue working on your current show. There is an exception with filming a movie" so Cameron had to choose. He chose Gamers Guide.
In some episodes, there are references about the movie, Grown Ups 2, and are said by Luke. Luke, Cameron Boyce, plays a role in both the Grown Ups movies. Also Adam Sandler guest stars in the episode "Punch Dumped Love"
The trivia items below may give away important plot points.
In one episode, Emma runs away to the Tipton Hotel where Mr. Moseby (Phill Lewis) is working. After giving Jessie some advice, Mr. Moseby is on the phone with Cody Martin (from The Suite Life series) and says, "I'm telling you, Cody--this girl looks just like Bailey!" Before playing Jessie, Debby Ryan was Bailey on The Suite Life on Deck.
In the episode where Ravi, Luke, and Bertram get stuck in the tea cup the sign says Tipton Tea. Debby Ryan (Jessie) used to play Bailey in Suite Life on Deck aboard the SS Tipton for high school. In a later episode Emma runs away to the Tipton Hotel where The Suite Life of Zack and Cody took place and Phill Lewis (Mr. Moseby) makes an appearance.
Though it is well known that Mr. Mosby (Phill Lewis), a character from the Suite Life on Deck appears in "Karate Kid-tastrophe", Matthew Timmons (who portrayed Woody on the Suite Life on Deck), another ex-castmate of Debby Ryan made an appearance in "Caught Purple Handed"
Ravi names one of Mrs. Kipling's baby lizards Gupta and in the other TV show he stars in, which was Bunk'd he said that one of his middle names is Guptanium. He also starred in Diary of a Wimpy Kid as Chirag Gupta