At first glance, the terms 'pianist' and 'keyboardist' appear to be virtually identical. True to form, most people use the two interchangeably when describing someone who plays an instrument with black and white keys, regardless of whether the instrument itself is acoustic or electric. However, the argument can be made that the difference between 'pianist and a 'keyboardist' is not purely semantical, but that the terms describe performers of two quite different instruments, each with a specific set of skills and a different function within the realm of music performance.
A pianist's proficiency will be judged based on how well he plays Chopin's etudes, improvises over the changes to Moment's Notice or accompanies a singer or other instrumentalist. Somewhat counterintuitively, a keyboardist's proficiency should be judged based on how well he knows and transitions between the different sound patches on his keyboard or synthesizer, and how he applies those patches to the music in the context of an ensemble. This is not to say that keyboardists don't need to have good piano skills; the technical requirements of the keyboard chair are no less demanding than those of any other instrument, and keyboardists are expected to play both written passages and improvised solos that would be impossible without a certain level of skill. Besides, they should theoretically have the same technical training as pianists, since both pianists and keyboardists almost all start out playing on acoustic pianos. But where technique is arguably the most important quality in a strong pianist, stylistic knowledge and application are of utmost importance for a keyboardist.
How does this relate? Cruise ship musicians fall into one category or the other. Piano bar entertainers and classical soloists or ensemble members are all, quite simply, pianists. Piano players in rock bands, lounge duos, Caribbean duos and, most notably, orchestra pianists should all be considered keyboardists, based on the fact that their stylistic interpretations of the songs they play and the patches they use to play those songs are the most crucial in terms of positively contributing to their respective ensembles.
Many orchestra pianists come from jazz or classical backgrounds. They therefore have strong technical skills, but often struggle to adapt to a setting in which basic triads, string pads and synth patches are the standard fare. There is still definitely room for creativity through fills, solos and the general interpretation of songs. But sometimes it is equally as difficult to curtail a keyboard player's habit of sixteenth note runs and tritone substitutions as it is to promote the increased technical proficiency and creativity of a less-skilled keyboardist. In other words, "less is more" is a concept which can be quite difficult to instill in players who have grown up in the types of settings that encourage virtuosic displays or crunchy harmonies. The ability to play blazing fast jazz patterns is, in general, way less important than simply knowing to use a string patch instead of a piano patch during Michael Jackson's Billie Jean.
Again, the goal is not to promote the hiring and appreciation of technically weak players on the presumption that they will make up for what they lack in finger speed and coordination with good style and patches. The crux here is the shift of awareness that needs to occur for many pianists, in both the orchestra and in other bands and ensembles; the prioritization of organs, strings and Rhodes patches and the concept of simple 'comping' that will ultimately contribute the most towards a great ensemble sound and win the respect and appreciation of your fellow bandmates.