"So what's the difference between the Phat and the Slim?
The PSP Slim offers a 19% slimmer (reduced to 18.6 mm from 23 mm) and 33% lighter (reduced to 189 grams from 280 grams) system than the original PSP system. Internal changes to achieve this include the removal of a metal chassis (used to reduce damage in the event of sudden trauma to the system resulting from the user dropping the system on a hard surface), improved WLAN modules and Micro-controller, and a thinner and much brighter LCD.
To target the original PSP generation's poor load times for UMD games, the internal memory (RAM and Flash ROM) was doubled from 32 MB to 64 MB, which also improved the web browser's performance.
To make the PSP slimmer, the capacity of the battery was reduced by 1/3. Due to more efficient power usage, the run time of the PSP is still the same as the older model. Older model batteries will still work which extends the amount of playing time. However, the battery cover on the newer model does not fit over the older battery due to its bulkier size
The PSP Slim & Lite has a new gloss finish. The serial port was also modified in order to accommodate a new video-out feature (while rendering older PSP remote controls incompatible). PSP games will only output to external monitors or TVs in progressive scan mode, so televisions incapable of supporting progressive scan will not display PSP games. Non-game video outputs fine in either progressive or interlaced mode. USB charging was made possible (the PSP Slim will only charge while it is in "USB mode". It cannot be charged via USB when playing a game). However, there are unofficial USB charge plug-in downloads for charging the PSP with a USB without the need for being in USB mode. The D-Pad was raised in response to complaints of poor performance, while buttons offer improved responsiveness.
A new simpler and more compact UMD loading tray design was developed, in which the tray swivels out instead of opening up completely, while the Wi-Fi switch was moved to the top of the PSP. To address many consumer complaints about the Memory Stick door breaking off the old PSP, the Memory Stick door has been relocated and redesigned. The speakers were repositioned on the front of the PSP near the top of its screen. The infra-red port was also removed because it offered no use to the original PSP generation other than in homebrew applications. Its analog stick was also redesigned to be more flexible and is not removable without opening the PSP. The air vent at the top of the original was also removed.
"
