Google reCAPTCHA is now used for captcha. The old image-based captcha is no longer available. Note that if you were using the old captcha, it will be disabled until the new reCAPTCHA Settings (AppConfigs) are configured.
LESS is now used for generating CSS stylesheets in the default skin.
A new “Shipping.Hide.Options“ AppConfig was added to allow hiding the checkout shipping options once an options is selected.