Difference between `always_comb` and `always_ff` block in SystemVerilog

In SystemVerilog, `always_comb` and `always_ff` blocks are used for different purposes.

1. `always_comb` block:

The `always_comb` block is used for combinational logic in SystemVerilog. This block is used to define logic that is evaluated whenever any of its inputs change. It does not include any flip-flops or memory elements. This block is executed in zero simulation time and is commonly used for sequential logic.

2. `always_ff` block:

The `always_ff` block is used for sequential logic in SystemVerilog. This block is used to define logic that includes flip-flops or memory elements. The `always_ff` block is sensitive to the clock signal and is used to model synchronous logic in hardware designs. It is executed at a specific time point based on the clock signal edge.

It is important to use the appropriate block based on the type of logic being implemented in the design to ensure correct functionality and timing.