The line weights generally represent the importance of a road. Railway Pde is a tertiary road. Frenchmens Road is residential road which is your normal street. Waterfall Road is an unspecified service road (speckled appearance indicates unpaved) which usually indicates a graded access road, and often these are used for roads that do not have formal reserves. The brown dotted line is a "track" which is typically an ungraded access track that is possibly unsuitable for regular traffic/low clearance cars. Aharvey has changed the Bunjaree cottages access track to a "driveway" service road, which is emphasised lower than Waterfall Road but higher than "track".
I understand there may be some overlap and ambiguity between some of these classifications, it's really up to individual discretion in most cases.