Raj Kapoor's achievements.

As a director Raj directed seven movies that were each the biggest hits of the year's they were released in:

1. "Ram Teri Ganga Maili" (1985)
2. "Prem Rog" (1982)
3. "Bobby" (1973)
4. "Sangam" (1964)
5. "Shree 420" (1955)
6. "Awaara" (1951)
7. "Barsaat" (1949)

Source - https://www.imdb.com/list/ls009418032/
Three industry hits:

1. Barsaat (1949)
2. Awaara (1951)
3. Shree 420 (1955)

Source: https://www.imdb.com/list/ls027134343/
Definition of a Industry hit:
"A movie that sets new record in full run shares is called an Industry Hit. It crosses full run( closing) shares of previous Industry Hit."
https://www.cinejosh.com/news/3/40787/definitions-of-movies-statuses.html
Other actors like Amitabh, Dharmendra, Shahrukh, Sunny, Salman, Hrithik Roshan each have only one industry hit (Sholay, Gadar, Dhoom 2, Chennai Express, Hum Aapke Hain Koun!). So Raj was three times bigger of a star than each of those six actors.
Five films where Raj Kapoor himself was acting (not just directing) and all were biggest hits of the years they were released in:

Sangam (1964), Anari (1959), Shree 420 (1955), Awaara (1951), Barsaat (1949).

https://www.imdb.com/list/ls009418032/