Salesforce Corner

A  question why lightning web component when developer already invested efforts in learning lightning component (aura component)?

lwc is based on standard web component that uses native browser technology or standard web technology modern Javascript ,html and CSS.
The benefit is to make things open to other platform  and  salesforce approach is also contributing towards develop open web standards.

earlier we were having lightning component based on aura component programing modal which  support ES5 and few feature of ES6(unable to find document what exact feature but it look like just promise from ES6)
where as lwc is using ES6+ advance javascript or modern Java script which make more sense to go for technology upgrade adoption.

Co- existance of aura and lightning
Many of us having question if lwc and LC(aura component) can co exist? Answer is yes but with a understanding of  Facet and slot

also as per understanding lightning aura can contain lwc but vice versa doesn't hold true https://developer.salesforce.com/docs/component-library/documentation/lwc/lwc.migrate_decide

now let's have look at composition structure ":"and "-"

lets talk about base component in side aura component

g:reco

rdform>
now lets have a look at lwc base component

namespace:component lightning:Card (lightning base component)
namespace-component lightning-card (lwc)

also lightning aura can contain lwc but vice versa doesn't hold true
https://developer.salesforce.com/docs/component-library/documentation/lwc/lwc.migrate_decide

to be continued .......