An Edit Validate rule is used more for pattern masking, for example a phone number has a pattern of (###) ###-####, so you can use an Edit Validate rule to implement. Therefore, when you reference an Edit Validate rule on a property, this pattern is enforced wherever the property is used.
A Validate rule can do more, and can be used for performing conditional evaluation to validate fields. Since Validate rule require an explicit call to execute, it is typically called in a Flow Action, after users have populated some values via a Section rule. Therefore, the validation is done only when it is called in a Flow Action.