Smd packages just means the type of board mounting a component requies. For example, the common LED that you see is a "through hole" type, meaning they have pins that you solder through holes on a board. SMD is a surface mount type, meaning there are no pins but instead, they require soldeing very small points that directly attach to the surface.
Smd is a lot trickier to solder if you have limited soldering experience since there's a greater chance of burning components or bridging solder traces accidentally. I would avoid it unless you know how to work with that sort of stuff, but 30 is a fair price for 100 white leds from my experience.
P.s.
I have not checked the link because I'm posting from my phone, but smd leds usually are packaged in a tape/reel. You must remove them from the packaging before u can use it. However, they do sell presoldered leds on a ribbon that you could buy ay different lengths. They are not addressable, meaning they all turn on or off, you cannot do light patterns