Sentinel vs. Sentry

Not much. A sentry is more military.

Mister MicawberNot much. A sentry is more military.

If one were to personify an inanimate object, such as a tree or an arch, I think sentinel would be the choice.

A sentry is generally a soldier performing a specific duty, sentry duty (guard duty), guarding a gate, building, vehicle, whatever, usually with special instructions. A sentinel often performs the same duty, sentry duty, but with the benefit of special training, not just instructions. Often sentinels set their own priorities and hold greater freedom of action. Such as 'protect this point of ingre

A sentry guarding a base for example would guard a specific point of entry. A sentinel would guard the entire installation with much greater freedom of movement and ability to challenge. Standing orders are also different. The US military generally uses MPs and doesn't call them sentinels.