Template part vs Sidebar (differences)

The get_sidebar($name); function loads sidebar template file sidebar-{$name}.php if no name in the prentacies is specified it loads the sidebar.php file.

get_sidebar() and get_template_part() are almost identical, at the end they call locate_template() function that take care of loading from files.

The only difference is the hook fired. If you use get_sidebar() for all your widget areas you can target them all later with get_sidebar hook if needed.

So both options are equally valid in terms of code. They differ in semantics as sidebar usually contains a dynamic_sidebar() area inside the template.