- DO NOT compare metrics in different user stages.
- Understand the definition among different tracking / analysis tools.
Let me try to give a detail explain.
Impressions / Clicks in GSC:
they are the metrics track user behavior in Google Search, you can check the definition in Google's document, in a word, simply but not that accurately, you can understand a show is a impression, a click is a click (as the word implies)
Traffic:
OK, forget this word if you want to real understand and explain, there is no "Traffic" as metric, or say there are a lot of metric can be defined as "Traffic", it's a very general word.
Page Views can be traffic, Visits can be traffic, Visitors can be traffic, Unique Visitors can be traffic, Demands can be traffic, Leads can be traffic, Instances can be traffic, and etc.
- assuming you are talking about Page View, a Page View (or customized views) can be counted or collected by web tracking system such as GA, AA when the implemented tag in the webpage got fired and target server well receive it, collect and classify it.
to make this simple, here is a scenario:
- user A searched a term, your webpage got displayed, 1 impression
- user B searched a term, your webpage got displayed, 1 impression, user clicked on the result, 1 click, user landed on your webpage and all coding launched well, no network issue or any issue, you got 1 Page View
- user C searched a term, your webpage got displayed, 1 impression, user clicked on the result, 1 click, user landed on your webpage but then network issue or s/he immediately click "stop" on browser or the coding issue, page not fully loaded, 0 Page View, coz the tag is not fired.
- user D searched a term, your webpage got displayed, 1 impression, user clicked on the result, 1 click, user then immediately found s/he just unintentionally clicked your webpage, s/he close the tab/window or no window/tab got opened, 0 Page View, coz the tag is not fired.
in above 4 scenarios, you got 4 impressions, 3 clicks but just 1 page view, so the "traffic" in GA is different to click in GSC.
About the rest of metrics, visits, visitors, unique visitors, different tools have their own definition to count, you may need to do further researches, but hopefully above replies could help to your OP.
Note: if the gap between click and page view is more than 10%, check your tag or ask your DEV team to check coding, server issue, etc. if the gap is more than 30%, and you are using advertisement agencies, running campaigns, pay attention to what the agency's action and use some anti-fraud traffic tools to identify, or talk to the agency to adjust their KPI.
