Long story -
Monarch is higher end, focus quicker and the optics are better. It costs more. Hey, you only buy binos once in a long while.
So don't buy and change, buy and change. Get the better one - get it right the first time.
All lenses and prisms are multilayer-coated for the brightest images
Phase-correction-coated roof prisms for high resolution
High-reflection mirror-coating prism for bright image
High-eyepoint design provides a clear field of view, even for eyeglass wearers
Close focusing distance: 2.5m
Eco-glass optics that are free of lead and arsenic are used for all lenses and prisms
Waterproof (up to 1m/3.3 ft. for 5 minutes) and fog-free with nitrogen gas
Turn-and-slide rubber eyecups facilitate easy positioning of eyes at the correct eyepoint
Rubber armouring for shock resistance and a firm, comfortable grip
Lightweight body uses fibreglass-reinforced polycarbonate resin
Can be fixed to a tripod using optional tripod adaptor
There was an old thread on this subject with detail explanations contributed by forumers. That was when I started searching for bino. In The end I got myself monarch 8x36 ATB. Very good quality and cost me 300 plus.
The value propositions for good binoculars is rapidly evolving. What used to cost a few thousands is now almost available for mere hundreds. I could not have imagined a Zeiss bin for $400 plus a few years back. Rather good initial reviews.