Nokia N81 vs Nokia N91
| Type | Slide | Flip |
| Dimensions | 102.00 x 50.00 x 17.90 mm | 113.10 x 55.20 x 22.00 mm |
| Weight | 140.00 g | 164.00 g |
| Display size | 2.40" | 2.10" |
| Display | Color / TFT 16M colors 240 x 320 px (2.40") 167 ppi | Color / TFT 256k colors 176 x 208 px (2.10") 130 ppi |
| Display protection |   | |
| Additional display | | |
| Protection of the secondary display | | |
| Talk time (max.) | 2G: 240 min. (4.0 h) | 2G: 240 min. (4.0 h) 3G: 180 min. (3.0 h) |
| Stand-by (max.) | 2G: 408 h. (17.0 days) | 2G: 190 h. (7.9 days) 3G: 170 h. (7.1 days) |
| Standard battery | Li-Ion 1050 mAhBuy powerbank
| Li-Ion 900 mAhBuy powerbank
|
| Quick battery charging | | |
| Wireless battery charging | | |
| Internal memory | 12 MB | 4 GB |
| RAM memory |  | 64 MB |
| Memory cards |  microSD, microSDHC up to 8 GBBuy memory card | |
| Operating system | Symbian 9.2 | Symbian 9.1 |
| Interface | Series 60 3rd Edition | Series 60 3rd Edition |
| Processor | ARM11 | ARM9 |
| Processor clock | 369 MHz | 220 MHz |
| GPU | - | - |
| Touchscreen | | |
| SAR (10g) | 0,96 W/kg | 0,67 W/kg |
| DualSIM | | |
| Other names | - | - |
| GSM frequencies | 850 900 1800 1900 | 900 1800 1900 |
| UMTS | 2100 | 2100 |
| LTE standard | | |
| CDMA | | |
| Standard TD-SCDMA | | |
| UMA | | |
CAMERAS - BACK
| First camera | | |
| Photo matrix | 2 Mpx | 2 Mpx |
| Resolution | 1600x1200 px | 1600x1200 px |
| Optical zoom | | |
| Digital zoom | 20x | 20x |
| Flash | LED | |
| Dual-colour LED flash | | |
| Video resolution | 320x240 px | 352x288 px |
| Video formats | H.263, MPEG4 - 15 fps | H.263, MPEG4, RealVideo 8 |
| Additional | - | - |
CAMERAS - FRONT
| First camera | | |
| Photo matrix | | 0.3 Mpx |
| Resolution | 320x240 px | 640x480 px |
| Optical zoom | | |
| Digital zoom | 2x | |
| Flash | | |
| Dual-colour LED flash | | |
| Video formats | H.263, MPEG4 - 15 fps | H.263, MPEG4, RealVideo 8 |
| Additional | - | - |
SENSORS
| Accelerometer | | |
| Proximity | | |
| Light | | |
| Magnetometer | | |
| Gyroscope | | |
| Barometer | | |
| Altimeter | | |
| Gravity | | |
| Hall-effect | | |
| Iris scanner | | |
| Fingerprint scanner | | |
| Thermometer | | |
| Hygrometer | | |
Data transfer
| xHTML | | |
| WAP | v2.0 | |
| HSCSD | | |
| HSUPA | | |
| HSPA | | |
| HSPA+ | | |
| LTE DL | | |
| LTE UP | | |
| WIMAX+ | | |
| GPRS | | class 10 |
| EDGE | | class 10 |
| Bluetooth | v2.0 | v1.2 |
| A2DP Profile | | |
| HDMI | | |
| WiFi | v802.11 b/g | v802.11 b/g |
| WiFi frequencies | 2,4 GHz | 2,4 GHz |
| WiFi Direct | | |
| WiFi Display | | |
| DLNA | | |
| Miracast | | |
| WiFi hotspot | | |
| IrDA | | |
| USB | v2.0 | v2.0 |
| GPS | | |
| Beidou | | |
| NFC | | |
COMMUNICATION AND MESSAGING
| Call waiting | | |
| Conferency | | |
| Call forwarding | | |
| Push To Talk | | |
| Instant Messenger | | |
| SMS | | |
| EMS | | |
| MMS | | v1.2 |
| Dictionary | T9 | T9 |
| Swype | | |
| e-mail client | POP3, IMAP4, SMTP | POP3, IMAP4, SMTP |
| Hardware QWERTY keyboard | | |
| RSS Reader | | |
Multimedia
| Radio | | |
| MP3 | | |
| Stereo speakers | | |
| Audio Jack | 3.5 mm | 3.5 mm |
| HD Voice | | |
| Sound formats | AAC, AMR, M4A, MP4, MXMF, RA, WAV, WMA, eAAC+ | AAC, AAC+, AMR, M4A, MIDI, MP4, RA, WMA, eAAC+ |
| Polyphony | 64 voices | 64 voices |
| Video ringtone | | |
| Ring composer | | |
| Games | | |
| Java | MIDP 2.0 | MIDP 2.0 3D |
| Videophone | | |
| DVB-H television | | |
| TV-Out | | |
PIM AND ADDITIONAL FUNCTIONS
| Watch | | |
| Stopwatch | | |
| Alarm | | |
| Calculator | | |
| Currency converter | | |
| Organizer | | |
| Calendar | | |
| SyncML | | |
| Data and fax | | |
| Screensaver | | |
| Themes | | |
| Interchangeable covers | | |
| Voice dial | | |
| Speakerphone | | |
| Recorder | | |
| Vibrations | | |