In high speed machining field, you will frequently encounter these two terms: BPS & Look ahead

What is the difference between these two? How is the performance of a machine, one with higher BPS and the other with higher Look ahead, all other features being equal.
Example: "Fanuc 31i-B Plus" has BPT = 0.2 ms & Look ahead of 1000 blocks. And "Heidenhain TNC-640" has BPT = 0.5 ms & Look ahead of 5000 blocks.

Thank you in advance