Hi vortix2950,
I'm not sure what method you're using to control your quadcopter, but if feels like it's trying to get airborne then gradually increase the proportional gain.
If the proportional gain is too low then the quad will feel sloppy and unresponsive, on the other hand if the P gain is to high the aircraft will begin to oscillate. The aim is to find that sweet spot between the two.
In rate mode the aircraft won't self level, as has no notion of which way is up, therefore it's left you as the pilot control maintain level flight with your transmitter.
But still feels the same. whats the benefit for the switch from servo?
The reason is somewhat historical. Traditionally ESCs were used for aeroplanes and helicopters. These aircraft require a smooth throttle response, therefore for these aircraft the ESCs software filter the raw the 50Hz PWM input direct from the receiver. (Most RC aeroplanes don't require a flight controller).
Back in the day, we're talking up to around 2013, quadcopter specific ESCs didn't exist like they do now. Unlike an aeroplane, a quadcopter or for that matter any multi-rotor requires a fast throttle response, in order to maintain flight stability and improve reaction time.
To improve the throttle response with aeroplane ESCs, flight controllers at the time attempted to essentially override the ESCs software filter, by increasing the update rate 10 fold, (50Hz to almost 500Hz). This causes the ESC's software filter to converge on the desired value more quickly, ultimately making the motor output more responsive.
Later, multi-rotor specific firmware became available and it was possible to flash certain ESCs to make them multi-rotor specific, but the 490Hz PWM standard remained. Nowadays there's a wide range of drone specific ESCs with a myriad of faster protocols such as: Oneshot125, Oneshot42, Multishot and DShot.
490Hz PWM was chosen because it's the maximum update rate that can be achived with 2000us pulses produced by a traditional RC receiver, (1/2000us = 500Hz). Also, much of the flight controller development at that time was being done using 8-bit Arduino boards, such as the Uno, Nano and Mega, and analogWrite() coveniently produced this 490Hz PWM frequency.