Answer 1:

Are different purposes and can be used together to optimize your website for different languages and regions.

Answer 2:

Benefits are Broader Audience Targeting, Simplified Management and Avoiding Duplicate Content Issues

Answer 3:

Using en-gb instead of en in hreflang attributes can offer several benefits, particularly if your content is tailored for a specific regional audience:

3-1: Improved User Experience.

3-2: Better SEO Targeting.

3-3: Reduced Bounce Rates.

3-4: Avoiding Duplicate Content Issues.

3-5: Enhanced Relevance.