Higher plans include more server resources (#1 factor in the WordPress optimization guide). Here’s the full comparison chart, but GrowBig gives you about 2x more server resources than StartUp, and GoGeek is semi-dedicated hosting which gives you even more. GrowBig and up comes with a free migration, staging, advanced caching, and ability to host multiple websites. GoGeek comes with priority support. Their cloud hosting is quite the price jump at $80/month.
If you're serious about making money online, start a blog. Blogging is one of the easiest and most sustainable income sources. As long as the blog is setup the right way, in the right niche, with the right content targeted at the right audience, and the offer is complementary to the content, you could make a tremendous amount of passive income from a blog.
Then once you’ve got your domain name and hosting sorted out, it’s time to pick a CMS, or Content Management System, that will let you update pages, build your blog and integrate with all the other services you need. It’s hard to go wrong with WordPress—the CMS powering close to a quarter of the internet. Keep in mind that eventually as you start growing traffic to your blog, you'll be wise to invest in a managed WordPress hosting plan from a company with great service like Kinsta, where all of the settings are custom-tailored and optimized to work particularly well with WordPress-powered websites.