HDCAM vs. HDCAM SR

I am hoping someone can help. I am trying to understand the real differences between HDCAM and HDCAM SR. I want to understand this in layman's terms...

From what I DO understand:
HDCAM SR 4:4:4 - records full RGB color
HDCAM SR -- 50% smaller particles than HDCAM to allow you to record all that color, which results in a higher recording density. All due to the smaller particles.

Now, HDCAM -- does that record in 3:1:1 or 4:2:2 - I am getting conflicting information?

Also, are compression rates a big deal when comaring HDCAM and SR? I know SR has a compression rate of 440/800 (HQ) mbps and HDCAM has 140 mbps... but what does this really mean? HDCAM compresses the data it is recording at a slower speed? Is that due to the smaller particles?

I also know that SR has twice the output of HDCAM... but once again, what does that mean? Twice the output of color sampling?

Any help you can provide would be great! Thanks so much!