just wanna know which one is better and what the difference is.

Steptronic.

This flexible features quickly transforms the six-speed automatic transmission in ur BMW to a six-speed manual. When the gear selector lever is moved easily to activate Steptronic (in the BMW 7 Series with a button at the steering wheel), u can shift gears up & down as with a manual transmission.
In the BMW 7 Series Sedan, gears can be shifted with no need to use the gear selector lever at all: by pressing the keys integrated in the steering wheel. These allow u to simply switch to manual mode in Steptronic when desired - ur hands stay on the wheel at all times. Two keys at the front serve to downshift, while two at the rear of the steering wheel r used to upshift. It also contributes to ur driving safety: u do not need to take ur eyes off the road for a moment,
triptronic does the same so l dont know the difference, l have a triptronic mercedes, used to have a bmw with triptronic too. sorry l cant help. l just use it in automatic :)

There is no difference, except in the name. Tiptronic was developed by Porsche, & there r many different names for the same function. Mercedes calls it TouchShift, BMW calls it Steptronic, but they r all automatic transmissions with torque converters.
A manual transmission that has no torque converter & shifts for u including the clutching action is what BMW calls SMG, or Sequential Manual Gearbox. VW calls it DSG, Ferrari calls it Superfast. Motorcycles also use a sequential gearbox, but not automatically. Technically, BMWs SMG is not a true sequential gearbox. The software will not let u shift from 5th to say 2nd without sequentially going through the gears, but a true sequential gearbox cannot skip gears at all, the BMW SMG is just a software controlled regular manual gearbox.

Marketing names
* Sport Shift- Toyota Celica GTS
* Quickshift - Renault
* 2-tronic - Peugeot
* Allshift, Twin Clutch SST - Mitsubishi
* Easytronic - Opel
* Durashift EST - Ford
* Dualogic - Fiat
* MultiMode, SMT (Semi Manual Transmission) - Toyota
* i-SHIFT - Honda
* Sensonic or ACS - Saab
* SensoDrive or EGS or BMP - Citroën
* Speedgear - Fiat
* Selespeed - Alfa Romeo, Fiat
* Softouch - smart
* Sportronic - Mitsubishi
* Duo Select - Maserati
* Automatic Stickshift - Volkswagen
* Sequentronic - Mercedes-Benz
* SMG/SSG - BMW
* S-Tronic - Audi
* Twin Clutch SST - Mitsubishi
* DSG (Direct Shift Gearbox) - SEAT, Skoda Auto, Volkswagen
* DCT - Volkswagen, Bugatti, Koenigsegg
* E-Gear - Lamborghini
* PDK (Porsche Doppelkupplungen) - Porsche
* AMT (Automated Manual Transmission) - Proton (carmaker)
Other users, Other manufacturers use Tiptronic-like systems under different names:
* Acura: Sequential SportShift
* Alfa Romeo: Sportronic, Q-Tronic
* Aston Martin: Touchtronic
* Audi: Tiptronic, Multitronic (CVT)
* BMW: Steptronic
* Chrysler/Dodge/Jeep: AutoStick
* Citroën: Sensodrive
* Ford (Australia): Sequential Sports Shift
* Holden: Active Select
* Honda: iShift, S-matic, MultiMatic
* Hyundai: Shiftronic, HIVEC H-Matic
* Infiniti: Manual Shift Mode
* Jaguar: Bosch® Mechatronic
* Kia: Sportmatic®
* Lancia: Comfortronic
* Land Rover: CommandShift
* Lexus: E-Shift
* Mazda: ActiveMatic
* Mercedes-Benz: TouchShift
* MG-Rover: Steptronic
* Mitsubishi: INVECS, INVECS II, INVECS III, Sportronic, Tiptronic
* Nissan: Tiptronic
* Opel/Vauxhall: Easytronic
* Peugeot: 2Tronic
* Pontiac: TAPshift
* Saab : Sentronic
* Skoda Auto : Tiptronic
* Subaru: Sportshift (system developed & name used under license from Prodrive Ltd.)
* Smart : Softip
* Toyota: Tiptronic
* Volkswagen : Tiptronic
* Volvo: Geartronic