Emerson and Thoreau were friends while they lived, both writers. Emerson was also importantly a lecturer. Thoreau was also a surveyor, doer of outdoor odd jobs, noticer of nature.

Now Thoreau is far more likely to be read voluntarily, spontaneously, not for school, than Emerson is.

It's sort of a classical/romantic split in the largest sense. Classical meaning carefully planned, solid, built in a logical way, and not carried away by emotion. Emerson's writing is like that. He's so careful and sober I can read some nasty or negative things he's written and not quite notice at first because he's stated them in such a sober grownup way.

The romantic, in the larger sense, is let by internal reactions than pre-existing ideas of what a work of art, an essay, should be like. The romantic starts with how the interaction between self and world feels, and gets structure from that. Maybe a fairly different structure for each piece. Thoreau.

Of course, all the arts, since they lived, have moved toward romantic.