Knowledge / Safety Measures / Watermarks / Differences

Watermark difference: common term for two postage stamps with no watermark agreement

Watermark design difference: common term for two the same postage stamps with no watermark design agreement

Watermark alignment difference: common term for two the same postage stamps with no watermark alignment agreement

Watermark quantity difference: common term for two the same postage stamps with no watermark quantity agreement (e. g. without or with watermark)

Watermark space difference: common term for two the same postage stamps with no watermark space agreement