Essentially only courts can record convictions (which give you a criminal record), impose prison sentences, community penalties, fines and discharges. If you are accused of speeding you will very often be given the opportunity to accept a �fixed penalty� (�60 and three points). If you accept this offer, you pay a penalty not a fine and you do not have a conviction registered against you.
However, this is purely semantics because the effect upon the individual is the same. They must declare the penalty when applying for motor insurance or driving jobs (the documentation usually refers to �convictions or fixed penalties�) and the points count for the purposes of the �totting up� procedure.
If, on the other hand, you are not offered a fixed penalty but are summonsed (because, for example, you were travelling at a speed so high that a fixed penalty is deemed inappropriate) the case will be heard in court. If you do not attend to enter a plea the case will be heard in your absence and, if the magistrates are satisfied with the evidence against you, they will convict you.
This is a �proper� conviction and as such gives you a criminal record. (Motoring offences are �criminal� offences, although the minor examples are viewed as less serious than �proper� criminal offences).