To answer this, we should establish what they both do. As a first time user, you have to set up the device you will present from... Which means you need to download an app for mobile devices, or for a computer, a small piece of software. This only has to be done once per device and from that point on, you simply run the software or app to project. If, for some reason, it is forbidden to install new software on a presenting computer (company security, perhaps), a USB flash drive is provided with the device from which the software can be run. No installation necessary.
Once your device is set up in this way, both the wePresent WiPG 1000 and the WiPG 1500 allow you to present over WiFi in up to 1080p high definition. They are both cross platform (Windows, Apple and Android) for presenting documents, slide shows, spreadsheets etc. Both models are secure, integrated, wireless access points which allow 64 users to be connected at a time, four of whom can display from their device to the presentation screen simultaneously.
They have a feature called Conference Control. Without using Conference Control, any of 64 connected users can project with the click of a mouse. Conference Control allows a moderator to control who is projecting, and where if there are more than one user projecting at once.
Browser Slides is another handy feature. Instead of supplying hand-outs or requiring the audience to take notes, Browser Slides allows your listeners to save screenshots from your presentation directly to their device.
SidePad Mobile Remote Control allows a presenter to remotely control a projection computer from his or her mobile device. A teacher or instructor can be behind the students controlling a projecting Windows computer with their Ipad!
Both the WiPG 1000 and the WiPG 1500 allow you to customize the software on it by placing your school or company logo on their splash screen for a more personally professional feel.
Now they part ways...
What is the Difference Between WiPG 1000 and WiPG 1500?
Beyond all the capabilities of the WiPG 1000, the WiPG 1500 contains a bit of a faster processor and in addition to the last similarity mentioned above about the customizable logo, also has the ability to let you customize the entire Start Screen. Also...
Touch Screen Integration! This is cool. You can connect a monitor with touchscreen capabilities or an interactive whiteboard and then control the projecting computer with the touchscreen... and do it all wirelessly.
Hotkey Shortcuts. Allow you to control where people are projecting on the screen.
Whiteboard/Blackboard Feature. This can be used even without a projecting computer. A virtual white or black board (your choice) allows you to write or draw using your choice of input device.
On-Screen Annotation. With this feature you can annotate your presentation from your own touchscreen device and the annotation will show up on the display in front of the audience
Sender For Galaxy (full mirroring). Now this is a cool trick! You can project exactly what's on your galaxy screen (tablet or phone) onto the rooms main display.
Both of these devices are the new hotness for classrooms, conference rooms and even peoples' living rooms. I look forward to seeing further proliferation of the wePresent devices. Just recently getting out of college myself, I know how much these are needed and how much they will enliven the experience for the presenter and those being presented to.