Vaadin 14 - What's the difference between select and combobox

In version 8 I used the setEmptySelectionAllowed method of the combobox.
Now, in 14 I read that the method is present in Select but not in Combobox.
Why ?
What’s the difference between Select and Combobox ?
Is there any way to emulate setEmptySelectionAllowed in combobox ?

Combobox has a search field to type in, Selectbox is like a normal combobox without searchfield.

Another difference is that the Selects Renderer is also applied to the selected value and not only to the dropdown-options. With the ComboBox, the selected value can only be represented by a String using ComboBox::setItemLabelGenerator.