Store/shop owner
You: May I see the manager or store owner?
I am the store owner. How may I help you?
Restaurateur
A person who owns and manages a restaurant
Store/shop owner（店主）
あなた: May I see the manager or store owner?（店長か店主にお会いできますか）
I am the store owner. How may I help you?（私が店長です。どうなさいましたか）
Restaurateur（料理店主）
レストランを所有し経営する人。
I would use the word "owner". If you wanted to be more specific, you could say "restaurant owner" if the person owns a restaurant, or "business owner" if they own a different type of business. "Business owner" can still also refer to someone who owns a restaurant.
Hope this helps! :)
The owner is the person who has legally bought the place and owns the land and building.
A boss would not technically be the owner but he/she would be the person who is in charge or responsible.
PIC (person in charge) does not have to be the boss or the owner but he/she is the person responsible for a certain area, store, restaurant, branch, etc.
owner は、その場所を購入し土地・建物を所有している人を指します。
boss は厳密には owner（オーナー）ではありません、boss はそこの責任者をいいます。
PIC (person in charge) は、boss である必要も owner である必要もありません。これは、特定の場所や店、レストラン、支店などの責任者をいいます。
"Owner" is usually the term given to someone who is the owner of normally a shop,business,restaurant etc.
"Boss/person in charge" often the Boss or person in charge is sometimes the owner of the establishment, but other times the 'owner' will hire someone to run the business (boss)
お店や会社、レストランなどの「オーナー」のことは普通 "Owner" といいます。
"Boss/person in charge"
'Boss'（ボス）または 'Person in charge'（責任者）が会社の 'Owner' であることもあります。あるいは 'Owner' が経営者（Boss）を雇う場合もあります。
The owner of something is the person that legally owns it
The boss is the person that is in charge but not always has to be the owner they might just be the manager
Shop/Restaurant owner explains what they own (shop or restaurant)
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アメリカ合衆国 
