The comparative studies of optical and structural properties of InGaAs/GaAs quantum dots grown in Stranski–Krastanov growth mode by molecular-beam epitaxy and metal-organic chemical vapor deposition is presented. An analysis of the photoluminescence at ultralow pump levels resulted that the quantum dots ensemble grown by metal-organic chemical vapor deposition exhibits photoluminescence corresponding to quantum dots ground state and at the same time ensemble of quantum dots grown by molecular-beam epitaxy demonstrates the bimodal behavior which can be explained by the presence of two characteristic ensembles of InGaAs/GaAs quantum dots with different sizes and different peaks of photoluminescence. The results on InGaAs/GaAs quantum dots studying by transmission electron microscopy are presented and discussed as well.