Hrm.. I don't think you understand the terminology. An image on a tv is produced a by lines, generally starting from the top left corner and working down horizontally. This is interlaced or when you see 1080i.
The same idea, just working down then starting back in the corner and working across is progressive or 1080p.
Component is generally 480p but can be 480i. These have 3 different cables for video and are generally thicker than composite. 2 more (red and white) for sound.
Composite is just yellow red and white. Yellow video, white left speaker, and red right speaker.
Component is better than composite because each colour is added separately giving a more colour range. However, these cables fit into composite slots and can still be used for composite depending on the device.
For an SDTV, I will almost guarantee that you will not be able to physically see a difference between these two inputs. For an HDTV, Component is significantly better.
I'm also not familiar with SDTV's having an input for component?