Top Slider - is a hidden container with module position "topslider"
What is it for? Any kind of module you want, which should be hidden but good visible as its click button is always top center, for example, announcment, note, warning, disclaimer, login, share buttons or any other which you think is the best place for it..
This element has the fallowing features:
1-4 parallel modules customizing backgrounds of container and button text fields for open and close buttons
Preloader is a template's component which hides the page showing nice effect(progress-bar or circular spinner) while the page will not load fully. So your your visitors will not see how browser builds the page, it's especially useful if you have too heavy pages or user has slow internet.