Buddhism and thought crime

Having read multiple sources about karma, there appear to be different interpretations. Some suggest that physical volitional acts bear the seeds of karma while others such as this one , suggest that karma is borne by thoughts. This is extremely confusing especially for someone new to the concepts since there doesn't appear to be an authoritative answer or reply. If there are "unwholesome" (since i don't know what are wholesome or unwholesome aside from causing direct harm with no ill intentions) thoughts, is this considered thought crime in Buddhism?