What many (and I daresay most) hosts call “WordPress hosting” is little more than a stripped-down version of a regular hosting plan, typically set up on a server that has extensive cache software installed, and either without a control panel or with a minimalist in-house-developed panel. The lack of cPanel/Plesk/DirectAdmin means the profit margins on these “WordPress hosting” plans are higher than with standard hosting, which is why hosting companies heavily promote them.
Oftentimes these “WordPress hosting” plans will have custom plugins and drop-ins installed that cannot be removed. Many will force automatic core/theme/plugin updates…whether you like it or not. And some hosts provide WordPress with core code that has been modified. These things are done to insure everyone is running the same basic WP installation, which reduces the need for support (typically the host’s largest cost).
Having said this, customized WordPress hosting plans exist where the host takes care of everything, including custom theme/plugin installation, and they offer quality support. Plans such as these tend to be expensive…up to 10X the price of a standard hosting plan.
Finally, here’s a tip: if you can hold off for a few weeks, most hosting companies offer “Black Friday” hosting deals that are usually their best prices of the year.