Launch, or rather Tags, is a tag management system.
Analytics is the analytics product. Traditionally, Analytics would be implemented in a website via the AppMeasurement library. So the data would flow as follows: website --> AppMeasurement --> Analytics.
Launch, or rather Tags, is a tag management system. As a TMS, it aims to reduce the coding effort needed mainly for analytics purposes. So the data would flow as follows: website --> Tags --> AppMeasurement (via the Analytics extension in Tags) --> Analytics.
Web SDK is the mechanism for sending data from the browser to Experience Platform, a new-ish product from Adobe. From there, the data can be sent to other endpoints, including Analytics. So the data would flow as follows: website --> Web SDK --> Experience Platform --> Experience Platform Datasets, Analytics, Target, Audience Manager, 3rd parties via Event Forwarding. If you use Tags, then the data flow would be: website --> Tags --> Web SDK (via the Web SDK extension in Tags) --> Experience Platform --> Experience Platform Datasets, Analytics, Target, Audience Manager, 3rd parties via Event Forwarding.
Mobile SDK is analogous to Web SDK, except that it is used in mobile apps rather than websites. But the data flow is still pretty much the same: app --> Mobile SDK --> Experience Platform --> Experience Platform Datasets, Analytics, Target, Audience Manager, 3rd parties via Event Forwarding.
Hope that helps!