What is the difference between Knight, Padawan, and Apprentice

Ok when I was watching TPM, I noticed the opening text stated that two Jedi Knights were on a mission of diplomacy. But Obi-Wan was still referred to as "Padawan" or "Apprentice".

So what is the exact difference between Apprentice, Padawan and Knight?

Apprentice and Padawan are the same thing. Knight is the intermittent stage between Padawan and Master. The referral to some as a Knight despite their actual rank is an arbitrary slip by the filmmakers/writers.

The terms "Jedi" and "Jedi Knight" are used interchangeably by the general populace and many OOU texts. In such cases, they refer simply to members of the Order rather than any particular rank.

Ah, thank you.