editing videos with 2 different resolutions

[OMGapotato]

I'm very new to video editing and i just found out about avisynth yesterday. i learned how to resize videos and link those videos with my editing software which is adobe premiere pro. the 2 different resolutions i have is the standard resolution and 720p. i understand if i use both resolutions for one type of sequence(hdv 720p or dv ntsc) then one resolution will fit and the other won't. is there a way to use 2 different qualities of sequences(for example, standard ntsc and hdv 720p) for one video? i want to make the lower resolution full screen while keeping the resolution of 720p the same. i assume this will create a contrast between the 2 resolutions but i also assume it won't make that much of a difference. thanks!

[Pwolf]

resize your 720p source. You can attempt to upscale but that's not really a good idea unless you know what you are doing.