Both the DT and DN let you create patterns of up to 64 steps, basically a four bar loop split into 16th notes. For the DT at least, you can have 128 “projects”, each of which has 8 banks of up to 16 patterns. So you can create a ton of these 64-step loops, and group them together in convenient ways. This is more or less the same as how most grooveboxes work. However, many other sequencers also allow for you to use a “song mode” (or some equivalent terminology) that lets you combine patterns together. So, say for example, you create a 64-step pattern that you want to play 4 times in a row as a “A” section to a song, and then another one you want to play 2 times in a row as a “B” section, many sequencers let you do that…you can usually save these specifications somewhere, and quickly recall “songs” this way. The DT doesn’t let you do that. You either have to “manually” change patterns while playing (which, tbh is quite easy), or you can use a feature called a pattern “chain” where you can specify the patterns you want to play and in what order. However, this feature is limited in that you can’t save these chains from session to session, and even within a session, they’re pretty easy to lose. So while both the DT and DN are super capable sequencers within a given pattern, they’re limited compared to many others in your ability to make longer compositions.
This limitation for both the DT and DN is source of great frustration and hand-wringing for many Elektron users. Most think that Elektron is withholding this capability principally because they don’t want to give these relatively “budget” models feature equivalency to their more premium boxes (the Ocatrack and Analog series).