The ISTDP I trained in was attachment-based, with focus on repairing the early attachment trauma to reduce maladaptive defensive strategies. I am not sure that is specific to time-limited dynamic psychotherapy. Am pretty ignorant about that though.
well to be tongue in cheek one was developed by psychiatrists (ISTDP) and the other by psychologists (TLDP). Both are attachment-based therapies that are more focused and goal-oriented than traditional dynamic treatment. Again to be tongue-in-cheek ISTDP is more intense, but it is. Patient may have longer sessions than 50 minutes or have several sessions in a week and may be encouraged to listen to tapes of sessions if meeting less frequently. Also watch the videos it is pretty intense in terms of focus on affects and a highly confrontational therapy. It is usually short term whereas in TLDP it is not uncommon for people to be in treatment for a year or longer (that's still time-limited for a dynamic therapy!) The former is shamelessly psychodynamic in nature, the latter integrates approaches from interpersonal and cognitive-behaviroal therapies as well. TLDP also focuses more on current interpersonal relations and patterns of relating and their impact on current distress. It also involves monitoring progress in a way more reminiscent of CBT than dynamic therapies.