1. Syntax: One key difference between Haskell and PHP is their syntax. Haskell uses a more functional programming paradigm with a strong focus on immutability, whereas PHP is more object-oriented with a procedural approach.

2. Strong Typing: Haskell is statically typed, meaning that all types are known at compile time, which helps catch errors early on. On the other hand, PHP is dynamically typed, allowing for more flexibility but potentially leading to runtime errors.

3. Concurrency: Haskell has built-in support for concurrency and parallelism through its lightweight threads and control mechanisms. In contrast, PHP lacks native concurrency features, requiring developers to rely on extensions or external tools for handling concurrent tasks.

4. Performance: Due to its functional nature and strict type system, Haskell tends to be more performant in certain scenarios compared to PHP, which is generally slower due to its dynamic typing and other design choices.

5. Community and Ecosystem: The Haskell community is known for its strong focus on purity, correctness, and advanced programming techniques, leading to more robust and maintainable codebases. In contrast, the PHP community is larger and more diverse, often emphasizing practicality and ease of use for web development.

6. Tooling and Libraries: Haskell has a powerful type system that allows for sophisticated tooling like type inference, static analysis, and advanced IDE support. PHP, while having a vast ecosystem of web-related libraries, may not offer the same level of tooling and developer experience as Haskell.

In Summary, Haskell and PHP differ in syntax, typing system, concurrency support, performance, community focus, and tooling capabilities.