Average cost per acquisition/action (CPA) is the average amount you are willing to spend on an ad to get a converision. This is done by dividing the total cost of conversions by the total number of conversions.
Bidding strategy that offers auction-time bidding capabilities that tailor bids for each auction. It allows you to define the value that you want to maximize, such as sales revenue or profit when you set up conversion tracking for your account.
Manual CPC lets you manage your Google Ads bids yourself. Allowing you to set different bids for each ad group in your campaign, or for individual keywords or placements depending on which ones are more profitable.
A smart bidding strategy with the goal of showing your ad on the absolute top of the page and anywhere on the page of Google search results by automatically setting the bids for you to achieve your impression share goal across all campaigns.