| Nokia 3660 | Nokia 6021 |
| Manufacture | Nokia | Nokia |
| Model | 3660 | 6021 |
| Form factor | Block | Block |
| Weight | 130 gram | 88.00 |
| Dimensions (HxWxD) | 130 x 57 x 26 | 106.00 x 44.00 x 20.00 |
| Operating System | Other | Series 40 |
| Networks | 2G - 900/1800/1900 | 2G - 900/1800/1900 |
| 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 | NA |
| DLNA | | |
| GPS | | |
| Glonass | | |
| ANT+ | | |
| IrDA | | |
| NFC | | |
| 3.5 mm audio connector | | |
| Camera | | |
| Camera resolution | 0.3 megapixels | NA |
| Image Stabilization | | |
| BSI sensor | | |
| Camera Flash/Light | | |
| Flash type | NA | NA |
| Video recording | | |
| Video capture resolution | NA | NA |
| Second Camera | NA | NA |
| Display size | 2.1 inches | 1.56 |
| Touchscreen | | |
| Colour display | | |
| Number of colours | 65536 | 65636 |
| Display width | 176 | 128 |
| Display height | 208 | 128 |
| PPI | 129.75 | 116.04 |
| Second Display | NA | NA |
| CPU | NA | NA |
| GPU | NA | NA |
| Memory | 3.4MB available to user apps. | NA |
| Micro SIM | | |
| Dual SIM | | |
| MP3 | | |
| Ringtones / Music file format | Polyphonic, WAV | Polyphonic |
| Java | | |
| Games | Java and Symbian | NA |
| FM Radio | | |
| Battery | Li-Ion 850 mAh | 900 mAh |
| Standby time (h) | 200 | 320 |
| Talktime (m) | 240 | 180 |
| Wireless Charging | | |
| Browser | 2.0 XHTML | NA |
| Calendar | | |
| Voicedialing | | |
| IP Code | NA | NA |
| Predictive text | | |
| RSS reader | | |
| Voicememo | | |
| PC Synchronization | NA | |
| SyncML | NA | |
| Website | Website | Website |