What Am I Looking At Here?

They are from the series 1902 the ones you make mention of above.

@YPOC - you seem to have understood very well, because those are exactly the three that belong together. As Jeff said, they are all from the same series, the series of 1902, and bear that inscription.

Now, if you already knew that, or that was obvious to you, then
a. you know more than you are saying about these stamps, and
b. perhaps you could be a bit more specific concerning what is confusing to you about the stamps you are picturing here.

How can we help you without wasting your time (or ours, for that matter)? What do you need to know?

As I said earlier, i'm new to this and I what I learn about stamps is what I read on the internet.

But it's still confusing to me what makes a stamp special, if you know what I mean here.
Some stamps are special because of perfins, cancels, perforations etc.

Just wanted to know if there was any stamp that stood out.