Both will be OpenType, but the 'Pro' version usually contains Central European characters on top of the standard set. So if you need Central European characters I would go for the Pro version.

'FF Meta OT 1' could've easily be called 'FF Meta Std 1'. Hope this helps.

The trouble is that every foundry has its own definition of "Pro". For FontFont it means additional language support -- CE, as Vincent said, but sometimes Greek and Cyrillic as well. You can check the PDFs on any OT font page at FontShop to see what's included.

The FF OT Collection brochure includes a handy matrix of language encodings.

> ‘FF Meta OT 1’ could’ve easily be called ‘FF Meta Std 1’

Except that every foundry has their own Std definition too. OT FontFonts include features and characters not found in the legacy formats, so they aren't a simple conversion to OT.

And "Std" is such a horrible name anyway.

>The trouble is that every foundry has its own definition of “Pro”.

History from September 2000... http://www.microsoft.com/typography/links/news.aspx?NID=1474

But what exactly makes an OpenType font a Pro font?

An Adobe OpenType font only gets the Pro designation if it has a minimum base character set and a reasonable number of OpenType features. The minimal Pro character set includes ISO-Adobe and Adobe CE character sets, plus the euro, litre, foursuperior and estimated symbols.

Can I call the OpenType fonts I make Pro fonts?

According to the OpenType list postings Adobe is not claiming any trademark on the Pro designation with reference to OpenType fonts. Although anyone is free to use the word, it would reduce end-user confusion if the type community remains consistent in their use of the term.

Need a webfont of Meta OT or a similar font. Any suggestions?

Meta on Typekit.

…or as downloadable, self-hosted fonts from FontFont.