The two options available from Lightroom Classic at no additional cost do two different things:
Lightroom Photos sharing lets you create a web photo gallery for a Lightroom Classic collection, when you turn on cloud syncing for that collection. Some collaboration with other users (such as review commenting) is possible through shared albums.
Adobe Portfolio lets you design a web page that can contain many things including a photo gallery, and one of the supported photo gallery sources is a Lightroom Classic collection.
You can publish an online photo portfolio using either tool. The main difference is that Lightroom Photos creates a photo gallery web page with limited options, and Adobe Portfolio lets you create a website of one or more linked pages. In Adobe Portfolio, you can customize the design, layout, and typography of those pages.
- If you just want to throw some photos on a web page and send people a web link, Lightroom Photos syncing works great.
- If you want to control the design of your web pages and add other content (custom headings, body text, colors; a mix of images from different sources, links to other websites, custom domain name…), then you want to build an Adobe Portfolio web site.