Comparing the crowd size of the anti-gun rally at Washington D.C. with the crowd size at President Trump's inauguration is like comparing apples and oranges, or perhaps more apropos, bullets and blanks. It is even more outrageous than the misleading comparisons between the inaugurations of President Obama and Trump that I wrote about in the Canada Free Press, "Response to Claim That More Women Protested [at the women's rally the day after President Trump's inauguration] Than People Attended the Inauguration," Jan. 23, 2017 (which includes a large section contrasting the Obama and Trump inauguration crowd sizes).
The inauguration of President Trump was on a weekday; the anti-gun rally was on a Saturday. Schools did not generally give students an opportunity to take off from school to attend the inauguration of President Trump; if anything, most schools are headed and staffed by people who opposed the results of the election that led to the inauguration.