Two pointers:
- Pointers move independently
- Can move opposite directions
- Focus on pairs or partitioning
- Examples: Two Sum, 3Sum, Container
Sliding window:
- Contiguous subarray/substring
- Left and right form bounds
- Usually both move right
- Examples: Max sum, longest substring
Key difference: Two pointers for pairs, sliding window for contiguous ranges. Sliding window is a specialization of two pointers.