prejudice isn't an action, it's a belief. you can be prejudiced but not discriminate for other reasons like social pressures or necessity. if someone's actions toward a particular member or set of members of a marginalized group appear non-discriminatory, that does not necessarily imply that they aren't prejudiced toward them.
for example, it's unpractical and considered immoral for someone who owns a restaurant to deny service to indian people, but that doesn't mean they can't hold a prejudice against them in private. they simply act as expected because that's what they know they have to do in order to be successful and accepted in society. in other words, prejudiced non-discriminators and non-prejudiced non-discriminators appear more or less identical to the outside world, but they still hold differing opinions. either way they should ideally have the same effect on society if their actions end up being the same, but they're still an starfish on the inside and that's what counts right