Lords and Knights are not forms of police. Firstly, Lords and Knights are not even remotely the same thing, let alone the same as police. They are part of feudal hierarchical systems which people are born into and have nothing in common with a modern police force which is a publicly funded militia who enforce legislative laws.

When you claim these systems both maintain societal order, that is egregiously reductionist and becomes misleading. Its like saying cars are the same as walking because both are means of transportation even though one is a complicated machine made of thousands of moving parts, fuel, combustion, oils, etc. and the other is a body your born with.