In the first case, each function pointer is checked one after the other whereas in the second it''s the whole feature that is checked.
For instance, with multitexture I wouldn''t like to write :
if (glActiveTextureARB) glActiveTextureARB(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, first_texture);
if (glActiveTextureARB) glActiveTextureARB(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, second_texture);
But according to your post, that''s what I should be writing !
No offense intended, just to clarify some points as usual.
RipTorn: if he buys a GeForce or a Redeon, either way he will have to deal with extension path so the topic is still useful anyway
