Two ideas can be contrasted with each other using the words whereas and while:
Real property refers to land and anything permanently attached to the land, whereas/while personal property refers to all other property.
Both whereas and while can appear at the beginning of the sentence as well:
Whereas/While real property refers to land and anything permanently attached to the land, personal property refers to all other property.
It should be noted that whereas is used in Legal English in two distinct ways. The first use has the meaning of “but on the contrary” (as un the present example). The second use is at the beginning of recitals, i.e. the setting forth of facts or other important matter in a deed, contract or other legal document.
Whereas, the parties wish to amend certain terms of the Sales Contract; and
Whereas, certain capitalised terms not otherwise defined herein are defined in the Sales Contract...
Amy Krois-Linder, International Legal English, Professional English, Cambridge.