The Kipor specs are unclear, but a non-inverter based
generator requires maintenance of certain rpm ranges to ensure proper output frequency (likely hence the digital moniker on the Tc model), whereas the inverter model is just taking a DC input and converting it to the proper frequency, likely hence the eco-throttle where the
generator can run at much lower rpm for small loads but still put out the appropriate frequency.
I am SWAGing all the above, but likely the Ti will run more quietly and use less fuel than the Tc model because it will be running at lower rpm -- That's about all I can guess about this.
If all you want is a small, relatively quiet generator, keep an eye on places like Lowes Lumber where they occasionally have good deals on returned/refurbished Mitsubishis with someone else's colors and name on them (Troybuilt).