If a team keeps another team at bay it means that they stay ahead of them in the match in a fairly comfortable manner. In the example above, Everton are leading Watford and with this phrase 'at bay' it suggests that they are not under too much pressure. They are keeping them at bay.

@dwi Difference and separates are both very similar - they explain that one team is leading the other, there is a difference between their scores. So, for example, Salah's strike (goal) is the difference between the two teams.

Sometimes we can use the word 'difference' to explain how one team is better than the other. For example, Salah was the difference between the two sides means that the two teams were evenly matched but one player's performance was much better than the others and helped their side to win.

• Manchester United's speed was the difference between the two sides
• Sancho's skill was the main difference between the two teams.

Thanks for the explanation, Damian.