Does a DC relay have positive and negative poles?

Whether a DC relay distinguishes between positive and negative poles depends on the specific type and design
1. ‌DC relays usually need to distinguish between positive and negative poles‌
The coil wiring of most DC relays (such as 24V DC relays) needs to distinguish between positive and negative poles, because the direction of DC power is fixed and the direction of the magnetic field generated by the coil is related to the direction of the current. If the connection is reversed, the armature may be attracted in the wrong direction, affecting the contact switching function.
Some DC relays will clearly mark the positive and negative poles on the terminals, for example, pin 13 is connected to +24V and pin 14 is connected to the negative pole. Reverse connection may cause the indicator light to not light up (but the coil may still work).
2. ‌Exception: Some DC relays do not distinguish between positive and negative poles‌
Some DC relays eliminate the influence of polarity through internal design (such as freewheeling diodes, resistors, etc.), and can work normally even if they are reversed. The direction of the coil magnetic field of this type of relay is not limited by the polarity of the power supply.
If the relay is only used to control passive dry contacts (such as normally open/normally closed contacts), and the coil is designed to be polarity-independent, the positive and negative poles connected to the opposite poles will have no effect on the contact opening and closing.
3. ‌Key difference from AC relay‌
Since the direction of the current in AC relay changes periodically, there is no need to distinguish between positive and negative poles; while the polarity requirement of DC relay depends on its electromagnetic structure design.