Look up or derive the frequencies of the standing waves of a length of wire, L, clamped at the ends and under tension.

Question

What are the similarities and differences between a vibrating string and a resonating pipe?
Does the diameter of the wire matter?
Does the diameter of the pipe matter?

I don't understand any of these questions and how to answer them.

Wavelength at resonance is dependent on the length of the wire, or pipe, and to a minor extent, the diameter. Your text has formulas for this.