@1
The Reti is characterised by the move c4, the King's Indian Attack by the move e4.
What is the difference between the Reti opening and the King's Indian Attack?
This is Reti
https://www.chessgames.com/perl/chessgame?gid=2290562
This is the King's Indian Attack
https://www.chessgames.com/perl/chessgame?gid=2292167

Reti is 1.Nf3.
Where the game goes from that point on depends on how black proceeds, and how white wants to continue.
One example:
Player's often use 1.Nf3 because of how flexible it is: they can transpose to various different openings, depending on black's defense.
The Reti usually transposes into something else: the English, the Queen's Gambit, the Catalan, the Sicilian (and so on ...)
The King's Indian is more specific in how white develops.
One example:
KIA development generally involves: Nf3, g3, Bg2, 0-0, and d3
Both of them seem to reach the same positions so am a bit confused.