| ViewSonic ViewPad 4 | HTC J Butterfly HTL21 |
| Manufacture | ViewSonic | HTC |
| Model | ViewPad 4 | J Butterfly HTL21 |
| Form factor | Block | Block |
| Weight | NA | 140.00 |
| Dimensions (HxWxD) | 121 x 66 x 11 | 143.00 x 71.00 x 9.10 |
| Operating System | Android | Android |
| Networks | 2G - 800/850/1800/1900 3G - 900/2100 | 3G - CDMA2000 1xEV-DO |
| HSCSD |  | |
| GPRS |  | |
| EDGE | | |
| UMTS | | |
| HSDPA | | |
| HSPA+ | | |
| WiMAX | | |
| LTE (4G light) | | |
| WLAN / Wi-Fi | | |
| Wi-Fi Hotspot | | |
| Wi-Fi Direct | | |
| SMS | | |
| MMS | | |
| | |
| HDMI out | | |
| USB port | | |
| MHL | | |
| Bluetooth | | |
| Bluetooth version | NA | 4.0 |
| DLNA | | |
| GPS | | |
| Glonass | | |
| ANT+ | | |
| IrDA | | |
| NFC | | |
| 3.5 mm audio connector | | |
| Camera | | |
| Camera resolution | 5 megapixel, autofocus | 8 megapixel |
| Image Stabilization | | |
| BSI sensor | | |
| Camera Flash/Light | | |
| Flash type | NA | LED |
| Video recording | | |
| Video capture resolution | NA | 1080p |
| Second Camera | VGA (640 x 480) | 2.1 megapixel |
| Display size | 4.1 inches | 5.00 |
| Touchscreen | | |
| Colour display | | |
| Number of colours | 16000000 | 16777216 |
| Display width | 480 | 1080 |
| Display height | 800 | 1920 |
| PPI | 227.55 | 440.58 |
| Second Display | NA | NA |
| CPU | 1 GHz Qualcomm MSM 8255 | 1.5 GHz quad-core, Qualcomm Snapdragon S4 APQ8064 - MDM9615 |
| GPU | NA | NA |
| Memory | 512 MB | 2 GB RAM. 16 GB internal storage |
| Micro SIM | | |
| Dual SIM | | |
| MP3 | | |
| Ringtones / Music file format | MP3 | MP3, AAC, AAC+, eAAC+, WMA, WAV |
| Java | | |
| Games | Yes | Yes, downloadable |
| FM Radio | | |
| Battery | NA | 2020 |
| Standby time (h) | NA | NA |
| Talktime (m) | NA | NA |
| Wireless Charging | | |
| Browser | Android HTML Webkit | Android HTML Webkit |
| Calendar | | |
| Voicedialing | | |
| IP Code | NA | IPX5 |
| Predictive text | | |
| RSS reader | | |
| Voicememo | | |
| PC Synchronization | NA | |
| SyncML | | |
| Website | Website | Website |