Li in the manga- Cardcaptor Sakura
Syoran Li is one of the many descendants of Clow Reed, an ancient magician who created the Clow Cards, magical cards that contained spirits of immense power. Born in Hong Kong, his family was known as the Li Clan, as all of them were highly trained and skilled in the generation and manipulation of magical energies. One day, Shaoran was sent alone over to Japan where the family owned a large house. He was on a quest to become the owner of the Clow Cards, which had become active ever since Sakura had begun collecting them. Though at first Li seemed to be an antagonist, always patronizing Sakura for her inability to understand the Clow Cards magic, he eventually grew to like her as she progressed and beat him to becoming the master of the Clow Cards. While Sakura was developing her magic, Syoran fell in love with her as she did to him, though niether of them admitted their love for one another until Syoran began moving back to Hong Kong. However, when Syoran and Sakura were older, Syoran inherited his families riches and was able to move back to Japan to see Sakura.
Li in the anime- Cardcaptor Sakura
In the anime adaptation of Cardcaptor Sakura, Li follows a pretty similar storyline as he did in the manga. However, in the anime Li was actually able to get his hands on some Clow Cards as there were 53, instead of just 19 in the manga. However, he still ended up having to give them to Sakura as she became their master. Unlike in the manga, Li and Sakura become friends lots earlier in the story as Sakura doesnt see him as threatening or agressive.
Li in Tsubasa Resivour Chronicle
In Tsubasa chronicle, Li and Sakura are older then before, about 17. Sakura is the Princess of the Kingdom of Clow and Syoran is an archeologist there. They are both deeply in love but have trouble meeting eachother due to the massive differences in rank. Again, Syoran is thrown into adventure when a mysterious power causes Sakuras heart to fly across the universe in the form of feathers. Each one has a power and, if they aren't collected, Sakura will die and the power could go into the wrong hands. In the manga, Tsubasa Chronicle adopts a very dark storyline, especially in the second half of the story.