So I saw this image flow through my Facebook wall,
and the implicit comparison struck me as so utterly wrongheaded that I needed to respond. On the face of it, to someone naive of racial history in the US, the comparison seems plausible. (Indeed, it fits into a rhetorical trope that speaks to the pattern-seeking nature of humans.) However, the naive logical parallel that comes when you say "'White Power' scares people who are not White; 'Black Power' scares people who are not Black" is only correct if both of the two movements are exactly the same on on fronts, except for race.
... but they aren't.
... not at all.
The only way that you could say that "White Power" = "Black Power" is if you compare the position held by the majority of people in the "White Power" movement and compare it with the extremists in the "Black Power" movement.
POSITIONS OF THE MOVEMENTS
The White Power movement is almost entirely embedded within the framework of White Supremacy, in which the goal is to attain White superiority over all other races. Depending on where and when you are talking about "White Power" in the US, this definition of "Whiteness" excluded several White races that weren't/aren't White "enough," since the definition of "White" (until relatively recently in the US) revolved around WASP-ishness. Therefore, if you were Catholic, you weren't "White." If you were Irish, you weren't "White." If you were Russian, you weren't "White." If you were German, you might have been "White" (so long as you weren't a Catholic German). And if you were/are Jewish, you weren't/aren't "White."
The Black Power movement formed around the goal of attaining equality for Blacks within society, with some groups advocating for a more militant approach. However, only a minority within the Black Power movement advocates for extending the mission of social equality to that of social dominance.
So, to recap:
White dominance over other races
Social equality for Blacks
Strong connections with white supremacist groups, like Neo-Nazis and KKK
Connections with Civil Rights Movement
One thing that you see in the image, is that the similarity of the hand gestures only accentuates the extremely naive parallelism that the words seek to engender. The people in the top-left panel are each raising their straightened right arms and yelling, and the people in the top-right panel are each raising their straightened right arms and yelling. So it seems that there is a parallel here, as well.
Neo-Nazi groups, which use the Nazi salute as a symbol of their group allegiance. Neo-Nazis are not - as a general rule - in favor of equal rights for non-Whites, which is why they tend to support the White Power movement in the US, and the use of a Nazi salute by supporters of White Power seeks to evoke the nature of superiorty of the White race over the others.
Black Power salute was born from an act of protest during the 1968 Summer Olympic Games in Mexico City, when sprinters Tommie Smith and John Carlos raised black-gloved fists as they hung their heads while facing the US flag as they stood on the winners' podium. This act of protest, during a period in which the US was suffering from "race riots" following the assassination of Civil Rights icon, Martin Luthor King, Jr., spoke to the problems that continued to plague many Black communities and Black lives. However, as evocative as it is, it is not the sole means of saluting "Black Power, and it was never tied to a regime or movement that advocates for racial domination of one group over others, as has the Nazi salute used solely within the White Power movement.
Equality for Black people with White people (and - by extension - other races) is not the same as dominance by White people over all other races. To place them next to each other in such a way as shown in the graphic is to tacitly imply that the two movements are somehow identical. And such an implied conclusion is just wrong, even though it does look rhetorically pretty.
AN ADDITIONAL PROBLEM WITH THE CONCLUDING IMAGE
Finally, an argument could be made that the pairing of these two images with the final image of "this is the only power that scares the establishment" does a great disservice to the Black Power movement by effectively shutting down the discussion about equal rights and the specific problems faced by the Black community. The line of reasoning is pretty much the same as to why stating "All Lives Matter" completely misses the point of the "Black Lives Matter" movement. The problem of effectively saying that racial harmony is important is that it effectively is saying that the Black Power movement (which is seeking racial equality for Blacks) is somehow asking for special treatment for only Black people... Which is like saying that LGBT rights movements are somehow askign for special treatment for only LGBT folks...
Or, to use Felonius Munk's explanation of why "All Lives Matter" is not really helping as a parallel: