These are all examples of personal property which typically convey with the house in the State of Maryland. When the seller executes a listing agreement with his agent he also fills out a Property Inclusion/Exclusion Addendum. The listing agent makes (or should make) this information available to the buyers and buyer's agent, it often is included in the seller's disclosure packet.
Buyers can see exactly which fixtures and personal property is included and whether or not there is anything that is specifically excluded from the sale. The Residential Contract of Sale includes a paragraph where all the applicable items can be checked off as well.
It is important to note that the Inclusion/Exclusion Addendum supersedes the Residential Contract of Sale in that respect. If the Addendum is part of the contract but lists different information, then that is what counts.
What about the pool table that fit perfectly into the basement? If it's not listed on the addendum then the seller wasn't planning on including it in the sale. However, that doesn't mean he won't consider it. It never hurts to ask!
All personal property should also be the same as of the date of contract execution. That means that the seller cannot just decide to take the brand-new stainless steel fridge to his new home and replace it with a 15 year old model. The personal property you saw and which is checked on either the Inclusion/Exclusion Addendum or the Residential Contract of Sale or both, is the personal property that conveys with the house.
Since it was done before the house was offered for sale, these mismatched appliances conveyed (unless the buyer's agent negotiated for replacement or a credit).
The missing vent was (hopefully) asked to be taken care of via the home inspection repair addendum.