They're a LOT different. Methaqualone is the active drug in Quaaludes, which was used as a CNS depressant (in the UK, it came combined with an anti-histamine and called Mandrax), somewhere between the benzos and barbiturates in action. Methylone is the cathinone analogue of MDMA, and is fairly similar in action to MDMA, but of shorter duration, and a bit less intense.
For the full effects to be felt, 150-200mg is the dosage range for the average person; it can start to become a bit much only a slight bit past the 200mg mark for some people, resulting in a light headed queasyness, that goes on to be physically uncomfortable. 75-100mg seems to be the absolute minimum for some sort of effect.
PS If you are interested, the dose of active drug in 'ludes (methaqualone) is about 250mg