Answers
What are the differences between the iPhone and the iPod Touch?
The iPhone is a cell phone - it requires a cell phone contract. The iPhone can connect to the internet via your cell phone service provider (almost anywhere) or WiFi.
The iPod Touch can only connect to the internet via WiFi. Older models did not include a camera or microphone, though these features are included in the most recent revisions.
Any model of the iPhone or iPod Touch has plenty of storage space to work with Reunion.
Please visit Apple's web site to compare different models and pricing of the iPhone and iPod Touch.
More information on the iPhone is here.
More information on the iPod Touch is here.