Ideological parties are those who base their existence on a particular (or set of) ideology. They are the parties most resistant to change, and least willing to sacrifice any given planks in exchange for a hand in power. While they will often broaden their platforms as they mature (going from single issue protests to filling in the rest of their policies) they tend to know where their core is, and will budge on that only at a glacial pace. The best (ie combining nearness to the archetype with likely familiarity by most readers) example of an ideological party would be the NDP (especially the earlier NDP). While there are certainly disagreements in policy, there are also clear red-lines and understood viewpoints. These parties, by their nature, tend towards the extremes of the political spectrums.
Personality parties are those parties who centre around a charismatic leader, who is often also the founder. By their very nature, personality parties tend to be smaller and more centralised, and work best in regional politics (although the further progression of TV and internet based campaigning is starting to change that). While the founder/leader is at the helm, they tend to be extremely resistant to gross changes in ideology, although depending on the ambitions of the leader, can also be amongst the most fluid and easily changeable on secondary issues. After the leader retires, these parties can experience massive upheaval, or even disappear entirely. The best example of a personality party is currently the ADQ with Mario Dumont, although even this isn't a perfect fit. Personality parties can be anywhere on the political spectra, from extreme left or right to dead centre, depending on the whims of the leader.
Power parties are those parties who major reason for existing is to hold power. They tend to be very large and always national (or provincial for elections limited to a single province) in scope. Both their policies and their presentation (which are occasionally at odds) are changeable at the more micro level, although will rarely venture outside the current popular fields. When they do experience more large-scale shifts, it is usually the result of a power struggle with competing views for what the 'average voter' would like best, and can occasionally result in strongly supporting policies that years earlier they opposed (or vice versa). The Liberal Party of Canada is the best example of a party based on power. Power parties tend to trend as closely towards the centre of the political spectra as they can, although will play to either (or both) sides if they see an opening.
Umbrella (grassroots) parties are easily confused with the previous style of party, but are fundamentally different in their motivations. They almost always share the size and scope of the power parties, but their policies are more malleable and will shift without the seismic upheavals necessary with the above. While there is a doubtless ideological bent to umbrella parties, there are always many outliers amongst their membership who will try to push the party in the direction of their choosing. The major distinction between umbrella and power parties are that umbrella parties are more willing to embrace policies that are supported by only a minority of voters if it plays well with their core membership - even if it results in some (though not overly significant) drops in electability. The Canadian example most akin to an umbrella party is the Tories. While generally avoiding the extremes of the political spectra, they are usually either to the left or right of centre.
Amazing what one is inspired to think of when confronted by skinheads (no, not in the shower). Thoughts?