Many people become mobile (able to get around without help) on inline skates faster than on traditional quad roller skates. That is because most recreational inline skates offer a lot of rigid support for feet and ankles, and the wheels extend much further to the front and rear which helps balance forward and backward momentum. As long as the goal is transportation, fun, fitness or outdoor skating activities, inlines may be easier and more practical.
Other new skaters find that the wide wheelbase provided by traditional quad skates helps them overcome their stability fears. But, these skates have all of the wheels under the ball of the foot and under the heel, so there is not as much front and back support.
If a beginner does not have a skating goal or skating discipline in mind, they can choose to learn in either traditional quad roller skates indoors or recreational inlines outdoors or indoors. The beginner techniques for these are similar and transferrable to whatever skating sport they finally choose.
If tricks, stunts and other advanced maneuvers are the goal, traditional quads are designed to these things and will allow more freedom with less skill. Inline skate designs have come a long way, so almost anything is possible in them, but for a novice who does not get specialized inlines, one foot turns, spins some jumps will require special effort on a rigid inline frame compared to a traditional quad frame with cushions for "steering" built in.
Quad roller skates and rollerblades both require balance, strength and stamina. The perceived degree of difficulty will differ from person to person. If you know what you want to do - speed, aggressive, freestyle slalom, figure, etc. - go for the skate that fits your activity, and try not to worry about what's easier. The easiest one for you will be the one you're having the most fun doing.