Linear sequencers, as opposed to Pattern-based sequencers, are working like a classic analogue multitrack recorder. Instead of working with 'patterns' or 'sequences' they work with tracks of virtual infinite length. The track behaves more or less like a timeline on which the notes and/or audio that is being recorded is being placed. After recording, the notes and/or audio can be clipped, moved and or copied to other regions of the track. Many functionalities that seems specific to Linear sequencers are reminiscent of tape-recorders: punch-in/punch-out for recording, scrubbing (slowly moving forward/backward with sound to find exact positions for edits) and of course the way you work with 'clips' which is exactly how in the old days the tape was 'edited', by clipping parts and putting them back together with stickytape.

The difference with Pattern-based sequencers is mainly that you can work in a 'song-mode' or 'track-mode' during the recording process and still go down a level to edit parts of the track (in most cases called 'clips' or even 'patterns', not to be confused with patterns in a Pattern-based sequencer). As you tend to do 'patterns' first with a Pattern-based sequencer there is no lower level to edit, only a higher level (where the patterns are arranged into a complete song or track).

Because of the way that Linear sequencers work they appeal mostly to people that are used to multitrack tape-recorders, record mostly Live played instruments and/or compose at song-level and do lower-level stuff during recording and arranging.

Some examples of Linear sequencers are Cubase, Logic, SONAR and in the cheaper range Podium.

Pattern-based sequencers are reminiscent of old-style analog hardware sequencers. This is mostly visible in the fact that Pattern-based sequencers place notes on a 'grid'. However, with modern Pattern-based sequencers you can move notes forward or backward in relation to the grid to create timing effects. Hardware sequencers sometimes had a 'shuffle' setting for each step to get that same effect but they where very inflexible in regard to todays software sequencers.

Pattern-based sequencers have a specific workflow that differs from Linear sequencers on specific points. The biggest difference is that with Pattern-based-sequencers you FIRST make the patterns that are afterwards arranged into a track or song. Because of this Pattern-based sequencers are used a lot for music-styles with repeating content like today's popmusic and of course House, Trance and similar styles. It would not be far fetched to think that modern dance music is a result of using Pattern-based sequencers and this is actually the case as modern dance music has a sweet spot for using old analog hardware gear, including hardware (step)sequencers.

Although Pattern-based sequencers seem to cater mostly to 'programmed' music styles, it is still possible to do more 'linear' things with them. Several Pattern-based sequencers like FL-studio and Orion Platinum can work with very long patterns, almost like tracks in a Linear sequencer. They also have great handling of incoming midi-information and can record audio as well. However, you need several workarounds if you want to record live players that are performing a complete track this way. Linear sequencers are simply better suited for that.

But for any track that consists of pre-defined patterns you can not get better than a Pattern-based sequencer, for obvious reasons.