The purpose of this study was twofold. Firstly to examine the relations between the different constructs that defines Nicholls' Achievement Goal Theory and Deci and Ryan's self-determination theory. Secondly to analyse the differences that exist between them with respect to the socio-demographic variables gender and age. A sample of 292 federated basketball players from the Region of Murcia (Spain) with ages between 14 and 18 years old was used. In addition, Castilian versions of The Perception of Success Questionnaire (POSQ) and the Sports Motivational Scale (SMS) were administered. Three statistical analyses were employed, a descriptive analysis, a correlation analysis and a regression analysis. The results showed a positive relation between ego orientation, extrinsic motivation and amotivation. The motivational relations between both theories and the differences with respect to gender and age are discussed. We have found out that mainly gender and also age differences are strong predictors of ego orientation, extrinsic motivation of external regulation and amotivation. We can also confirm that extrinsic motivation of external regulation positively predicts ego orientation and a decrease of task orientation. The results ratify the use of the Spanish version of the SMS to measure different types of motivation within the sports context.