I think your tiles need to be larger. Choose an interesting, but simple pattern similar to the one below. I also like the idea of something that is from the region you live. Without seeing your space it is hard to know. You say a stone fireplace, what kind of stone? You want the tiles to go, but to make the fireplace stand out do not go too matchy. Mixing concrete with the tiles can create interest, too.

I have a courtyard that I had a quote from Stratco to enclose into a room. They were going to use wall panels with windows and a sliding door. I ditched the project when I realised the costs were enormous as I'd have to excavate and repour the concrete and move some plumbing as well as look at heating/cooling options if I wanted to use it all year round.

On first impression It seems the design is inherently working against your desire to have the 2 spaces to "feel separate"; from the screenshot it looks like the kitchen bench design (same modules, colour etc) and the open shelving do not help by making the splash back of the 2 spaces "continuous". Rather than thinking just about different materials and colours - perhaps rearrange the storage/cupboard space to create more visual separation? For example: having some full height cabinets against that dividing wall and have the outdoor kitchen a different design altogether?

Face it - gravity sucks. Your house was designed to be supported by the "poles" or are they stumps? You will need to carefully assess the value in removing them all. First you will need to engage a structural engineer to advise you, and he may suggest long steel beams that run across from one side of the house to the opposite side allowing the supports to be removed. However the financial cost in installing these long beams (and additional structure to support the beam ends) will be significant - there is no cheap fix. Once you have paid tens of thousands of dollars (maybe more depending on the length of the spans and ease of access under your house for installing them) you will have a large, open, low-ceilinged space with the proportions and feel of a shopping centre carpark. The structural engineer will need deep steel beams depending on the span between the walls, and this will reduce the clearance under the beams to much less than your current 2.1 metres. Save your money and engage a clever designer to find a clever solution that works with keeping the supports, and you will get much better value for your spend. Best of luck with your considerations, Dr Retro of Dr Retro House Calls