Five Vs. Four
Here's the dirt on how these objects relate to one another:
5 is the successor of 4: 5=4+1. x=4 is the lowest solution to the inequality "5^x is less than x digits long" (that is, 5^4 is less than 4 digits, but 5^x is at least x digits for all x<4).
5 and 4 are part of a Pythagorean triple: 4^2+3^2=5^2. This is especially interesting as this is the first (lowest) Pythagorean triple in the usual ordering.
5 and 4 are part of a Pythagorean triple: 4^2+3^2=5^2. This is especially interesting as this is the first (lowest) Pythagorean triple in the usual ordering.
Metrics
Parity Five: odd. Four: even.
Parity Five: odd. Four: even.