Lenovo has several series in ThinkPad with each on its focus of uses. Lets categorise them in terms of entry-level to the high performing series.
1) E series - these are the entry-level ThinkPads reliable for browsing, office works, video calls. People in need of slight computational power
2) L series - they have the budget conscious business and students laptops who are in need for productivity the most with good battery life.
3) Z series - laptops for young professionals with good performance, sustainable materials and modern design.
4) X series - these are compact and portable laptops for travellers use with light weight with good performance and good battery life.
5) X1 series - ultralight laptops with high performance, vibrant display for travellers and students
6) T series - business flagship laptops for professional web designers and programmers. Offers balanced performance with good battery life.
7) P series - Powerful in the ThinkPad series and good for powerful computational tasks like 3-d modeling, video editing and gaming.