The one with BNC connectors is just a regular VGA cable. Some higher end monitors and video editing hardware had BNC connectors on them.

The Reveal cable was probably some specific cable for a Reveal branded video capture card or something like that. Good luck figuring out out the exact kit it came with.

The first one is to connect "professional" 1980s to early-1990s monitors with BNC connectors.
They are offered often on ebay, but there is little demand for them, as these old monitors commonly have low horizontal frequency. I once sold one for, I think, 5 euros.
The cables of that kind I still have I use for butchering, as they are very nice to connect multiple signals to BNC inputs without cabling mess.

The second one looks to me like some proprietary RGB/composite/stereo audio adapter.

Back in the day BNC cables were considered to have better signal characteristics than regular VGA cables. If you needed to do very high-res work, you'd try to use these if possible. There were more than enough high-quality and indeed high-refresh monitors available for them. My last non-retro CRT was a Sony GDM-W900 24" widescreen monster that I ran at 1600x900@75Hz. Its picture was visibly better via BNC than DE15. And that was by no means the best horizontal refresh you could get with BNC-fed monitors; its successor the GDM-FW900 could handle up to 121kHz.

As a rule the monitors with BNC were among the best of their day, if they seemed worse, it was because they were also among the most expensive, so price-for-price you were looking at significantly older monitors. If you forked out major cash for new ones, they were the bees knees.

dionb wrote:

...Sony GDM-W900 24" widescreen monster that I ran at 1600x900@75Hz. Its picture was visibly better via BNC than DE15. And that was by no means the best horizontal refresh you could get with BNC-fed monitors; its successor the GDM-FW900 could handle up to 121kHz.

I had one of these at work long ago.
These are great, but their weak point is their HOT. It likes to die after a few years, and as there is no replacement available, these monitors are practically extinct by now, long before their predecessors which had better HOTs.

Since I often read otherwise, I havent noticed any difference when using BNC cable or regular VGA cable (of reasonable quality such as those with ferrite ends) when using "modern" CRT monitors. On the contrary, the BNC cable does not have that pin for EDID information transfer which can cause some issues on its own. Personally I bother with BNC only when I need 2 computers hooked up and dont have a KVM switch.