Look here 
It’s an upgrade in the sense that it’s more powerful, you get official cPanel and more tools and support.
Some of the other numbers do go down, however the unlimited bandwidth and hosted domains on free hosting is not completely true (Bandwidth is more or less limited to 5GB by the hits limit and file upload limit combined, and I believe there is a limit on each type of domain you can add)
It’s also worth noting that on premium hosting the daily limits (RAM, CPU usage, hits, etc.) are much higher, and reaching them won’t suspend your account, only throttle it.
Starter Premium is more of a sidegrade than an upgrade from free hosting. It’s an intermediary step for people who want the features of premium hosting without the limits of premium hosting.
Whether Starter Premium is an upgrade or a downgrade for you, that depends on your needs.
So in some pricing tables, you don’t even see Starter Premium at all, and only see the Super and Ultimate plans. Because those are the real upgrades compared to free hosting.
It can be a upgrade or a downgrade depending on what you are trying to do
