I got one of these a few months ago and I’m happy with it. It looks very good and has held up through a few summer storms when I forgot to fold it. It will fade eventually and I’d get another just like it.
How does this one compare with the other umbrella being offered?
This is steel; the other is aluminum. Steel is stronger.
Bought the steel one last time around. Total junk. Left it on the curb and got a similar sized model at BB&B for $120 MSRP + 50% off end of season clearance + 20% off with the famous never-expiring BB&B coupon. It is ten times better.
What is the diameter of the umbrella?
Overall dimensions: 108-inch x 102-inch x 108-inch
108" or 9’ as noted in the titles. 
Can you use this at the beach? Would it be easy to transport,
Would it hold up in the sand?
That’s not its intended use. It weighs 11 pounds and would be pretty large to carry. Unless you have a way to secure it, it’s gonna blow away with the first gust.