Supravalvular pulmonary stenosis (SVPS) is considered a rare form of pulmonary stenosis (PS) and represents both a diagnostic and therapeutic challenge. There currently exist no reliable echocardiographic criteria to accurately predict the supravalvular form. The aims of the study were to describe the response to treatment of the different PS presentations and to outline the diagnostic capacity of echocardiogram to differentiate the SVPS from valvular PS (VPS). This retrospective study included 106 patients who underwent percutaneous angioplasty between 2006 and 2017. Interventional outcomes of patients with SVPS were compared to those of patients with VPS. Diagnosis of VPS vs. SVPS by echocardiogram was compared to diagnosis obtained by angiogram. Echocardiogram yielded a sensitivity of 56%, a specificity of 82.5%, a positive predictive value of 50%, and a negative predictive value of 85.7%. Patients with SVPS had a significantly smaller pulmonary artery to pulmonary valve (PA:PV) ratio. At 6–12 months of follow-up, the VPS group had a mean right ventricular to pulmonary artery (RV-PA) gradient of 21.68 ± 19.85 mmHg compared to 45.27 ± 24.58 mmHg in the SVPS group. Patients with SVPS had a higher rate of reintervention than patients with VPS (32% vs. 6.2%, p < 0.001). There was no difference in major complications between groups, whereas VPS patients had a higher proportion of pulmonary insufficiency. Percutaneous angioplasty for PS is less effective in patients with a supravalvular component. A better understanding of the underlying histopathology of different PS subtypes could lead to development of different techniques to improve outcomes, with fewer reinterventions, in this population.