What is the difference?
Combobox / Autocomplete vs Dropdown / Select
The difference is whether the user can type. A combobox is an editable text input that filters the list on every keystroke. A dropdown is a trigger that opens a fixed list you cannot type into. The confusion comes from ARIA giving both the same role, but the real separator is whether there is an actual text field.
Ask yourself one question
Are there enough options that the user would rather type than scroll?
Combobox / Autocomplete
حقل الإكمال التلقائيrole="combobox"Use it when
Long or open-ended lists: cities, currencies, usernames, or tags the user can add.
Full entryDropdown / Select
القائمة المنسدلة<select> / role="listbox"Use it when
A short, closed set the user already knows: a status, a sort order, a page size.
Full entryThe classic mistake
A combobox that wipes what the user typed on blur because it matched nothing. Either accept the new value or keep the text and say plainly that it matched no option.
Other comparisons