Help: difference between Beopt & OpenStudio

I am new to building energy modeling. I'm doing a research project on residential energy efficiency in Saudi Arabia and will use a building energy model in that research. Am I correct in that both Beopt and OpenStudio are front-ends to EnergyPlus? But that Beopt allows for optimizing a building design/technologies on cost-effectiveness?

But then, it seems that you can use Genopt with EnergyPlus (presumably in conjunction with OpenStudio) to optimize as well.

So what are the pros and cons of Beopt vs OpenStudio/Genopt?

And if I've misunderstood these options, please correct me. Thanks.

Yes, you are correct that both BEopt and OpenStudio are front-ends to EnergyPlus. BEopt was designed for modeling residential buildings, with a key focus on comparing multiple improvements for cost-effectiveness. OpenStudio wasn't necessarily designed to model residential vs commercial buildings, but most of its library resources (construction assemblies, schedules, internal gains, HVAC components) are for commercial buildings.

There is work underway for bringing the cost-effectiveness analysis and other features of BEopt into OpenStudio. You can read more about the subject in this post.