On Fri, 07 Jun 2013 11:50:34 -0500, dpb wrote:

They aren't necessarily the same; only that they fit same dimensions

That's exactly why I'm asking the question.

That pool pump motor bearing *size* is priced anywhere from $20 at pool
stores, down to $2 on Ebay, and every price in between.

So the question is how to best choose amongst the choices?

Fafnir, Federal, New Departure, Timken, SKF, NSK are ... well known.

That may be the simplest way to narrow the choices down.
By brand, and then by price.
Note: I called AO Smith (now Century Motors) and they said the original
bearings were NSK 6203 double sealed; so NSK may be the way to go.

price isn't all that helpful
Nonsense. All generalizations, are, in general, generally false...

I don't (yet) know how to choose bearings, but, having taken quite
a few economics & marketing classes, I find it hard to believe that
the pool store $18 bearing is really the best bearing.

To give an example of something that I do know - at Sears, for $75,
I can buy a US Seal PS-3868 pump seal, which I can just as well get
for $10 at a whole bunch of places online.

I find it hard to believe that Sears' pump seal is any better (or
even any different) than the same seal bought for $10. Point here
is that, price is absolutely no indication of quality. Never was.
Never will be.

(Note: Price, from Microeconomics 101, has much more to do with
Marketing, Demand, and Competition (although Chinese goods also
have a bit of Macroeconomic policy affecting prices).

you've still not given any indication of service need

Ooops. My mistake. Pool pump motors. 230v. I think they're about
4,000 rpm. Outdoor use. They run dry (if the pump seals are good).
They run for about 8 hours a day. 3/4" shaft. Original bearings
are NSK 6203 double-sealed, non shielded. Replacement bearings
currently were 6203D which is a substandard bearing, IMHO.