Yes, its a kind of seal script. The two halves form one zen phrase, but the first part is the most famous/referenced. The photo on the bottom should be the first line of the idiom/phrase, and the photo at the top should be the second line:
松無古今色
竹有上下節
New or old, the pine's color doesn't change,
The bamboo has nodes on the top and bottom.
The first phrase is intended to represent the timelessness, or unchanging nature of the universe.
The bottom phrase has a different nuance, and is meant to illustrate that even as a bamboo stalk is made of parts that have connecting ridges on the top and bottom of each section of the stalk, they all form the whole. In other words, both top and bottom (high and low, rich and poor, etc.) form the whole.
There is a good English explanation of this idiom at the Reddit link below