These terms originate from the movement of cargo but now they are gradually appearing in the field of passenger transport, as can be seen already in the 2011 "Characterization of Participants in Multi and Intermodal Transport" by Prof. Dr.-Ing. Regine Gerike (FIS (Forschungsinformationssysteme)).
Regarding these definitions, a multimodal traffic participant is using various alternating transport methods during his trip, e.g. in fair weather he is using his bike to go to work, and in bad weather he is using public transport or his own vehicle.
An intermodal traffic participant combines various transport means, e.g. driving to a Park & Ride with his own vehicle, and then using public transport for the rest of his trip.
We are used to getting advice from travel information systems when planning our trips, especially for rarely used routes.
Following these definitions, multimodal trip information is only a meta search ending up with a simple side-by-side display of the search results for different transport options. This method cannot optimize the results when searching the various connections - it can only filter out the bad alternatives after having received all the results of the search process.
Many options are also not able to transport the passenger "from door to door", if we consider, for example, flights and long-distance buses. Such modes of transport need the supplement of services to and from the airport / bus station - the so called "last mile problem". Often, the passenger has to solve this problem himself - and this does not greatly increase the attractiveness of those options.