First: What's the definition of the term Mikdash? I noticed that the Kehatim, where bearers of the 'Mikdash', "they shall bear", where it is in fact the Ark of the Covenant that is referred to as the 'Mikdash'.
Second: Whats the definition of the term Mishkan? The "Mishkan" in its more specific sense refers to the bottom layer of curtains: "YOU SHALL MAKE THE MISHKAN OF TEN CURTAINS, fine twisted linen and blue and purple and scarlet, [with] artistic keruvim shall you fashion them (Shemot 26:1)". In contrast, when it comes to the construction of the boards, we are told: "You shall fashion the boards FOR THE MISHKAN... (Shemot 26:18)". The boards are FOR the Mishkan, while the curtains themselves are the Mishkan.
And at last: Whats the definition of the term Ohel (when referring to the Sanctuary). "He abandoned the Mishkan of Shilo, the tent (ohel) where He dwelled among people" (Tehillim 78:60). In this verse and in Sefer Vayikra, "ohel" is the general name for the whole building. More specifically, "ohel" refers to the goat skins that were spread over the curtains of the Mishkan: "You shall fashion curtains out of goatskins as a covering (ohel) over the Mishkan; you shall make eleven curtains" (26:7).
I noticed that these terms are somewhat used interchangeably to refer to what we would call 'The Sanctuary' while sometimes they are used to refer to specific parts of the same 'Sanctuary'.
So what exactly is what? And is there a common denomitor between the contrasts given for each case while using the same terminology?