Does anyone have any thoughts or experience regarding differences in cornet and trumpet embouchures? For example, the cornet embouchure being more puckered - greater lip mass in mouthpiece (more space) and less requirements for extreme registers...some say that there is great similarities between horn and cornet embouchures as the play funnel mouthpieces....

In general a trumpet player will keep less lip in the mouthpiece (less space) and will be flatter (keeping the upper lip close to the teeth and gums) and firmer than a cornet player.

I am student studying at conservatoire level, recently come off 4 weeks heavy duty cornet playing at a decent level. I have found that my embouchure has gone so far foward into the mouthpiece that I am bottoming out on my main trumpet mouthpiece. It is proving difficult to get the lips out of the mouthpiece again and play with some type of mmm setting.

Any thoughts?

great question this is primarily why trumpet players who cross over to cornet or fluglehorn as i do always use the same size mouthpiece for all the insturments. reason being that little changes require little effort where large changes cause muscular failure in the lips due to diffrent rims more so than cup size. using the same rim is essential to endurance carmine caruso my old teacher stressed using the same rim for all the insturments hope this helps pat