Why my iPhone 7 Plus have the same housing as iPhone 8 Plus?

I have a iPhone 7 Plus, and I want to make a switch to iPhone 8 Plus for cheap, so I have a simple concern: given similarities in iPhone design, camera or casing,

is my iPhone 7 Plus housing the same as iPhone 8 Plus, or is there changes in housing?

can I or someone else just swap the parts in the iPhone 7 Plus with iPhone 8 parts, such as logic board, or should I just buy a new iPhone?

I would like to sacrifice wireless charging for a cheap upgrade.