Video Resolution for iPod 5G AND iPhone?

Here are the specs for supported video for both devices. Hope you can find what you want.

iPhone: Video formats supported: H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; H.264 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Baseline Profile up to Level 3.0 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats

5th Gen iPod: H.264 video: up to 768 Kbps, 320x240, 30 frames per sec., Baseline Profile up to Level 1.3 with AAC-LC up to 160 Kbps, 48 Khz, stereo audio in .m4v, .mp4 and .mov file formats.MPEG-4 video: up to 2.5 mbps, 480 x 480, 30 frames per sec., Simple Profile with AAC-LC up to 160 Kbps, 48 Khz, stereo audio in .m4v, .mp4 and .mov file formats

Use Handbrake and set the conversion. Be sure to download the latest version then click the gear wheel at the bottom of the sidebar/presets window which will give you the option to +Update built in Presets+ .
From there choose the "*iPhone and iPod Touch*" from the Apple presets.

I would say Yes, I've just had a look at the 5G it's screen shape is a completely different aspect ratio. They may likely play on both devices tho so I would first do one at the iPhone setting and see if the iPod accepts it and then try it the other way around.