Themes can be different in terms of overall design and layout. To change theme, you need to log in to the Wordpress administrator page, Hover on Appearance, click on Themes at the sidebar menu. In the Themes page, that is where you can change your theme. To change a theme, select the theme you want, then click on Activate and wait a few seconds to apply the changes. To enjoy your theme, just refresh your browser and the magic happens.