Psalm 1 is known as a "Wisdom Psalm." That is a categorization given to it by later interpreters not necessarily one it claims for itself. Even so, Psalms 1, 37, 73, and 128 resemble the Wisdom literature like Proverbs, Ecclesiastes, and Song of Songs.
The principle difference between the wickedness and righteousness within Psalm 1 is the approach each takes to instruction. The righteous embrace God's instruction; the wicked reject it. The Psalm begins with a beatitude (a statement about what it means to be "Blessed" or "Happy"). The beatitude describes the blessed righteousness as a three-part distancing ones self from wickedness. J. Clinton McCann of the The New Interpreter's Bible volume IV explains that the terms used in Psalm 1:1 get progressively more specific. "The wicked" is a general term for ungodly people. "Sinners" has the more specific meaning of those who miss the mark of meeting God's expectations. "The scoffers" are those who willfully reject instruction. This should not be confused with anti-intellectuals who can be problematic in their own right. The scoffers are those who regard faith instruction and consideration of God's commands as irrelevant or negligible. By contrast, the blessed/happy delight in God's law and meditate. Deep reflection on God's instruction marks the blessed; resistance to God's instruction marks the wicked.
The Psalm uses contrasting biological similes to describe the happy and the wicked. The reflective and teachable blessed one is like a great tree receiving sufficient nutrients from the river to also provide fruit to others. The Psalmist searches for the biological antithesis to the stable, rooted, and fruitful blessed one and finds this polar opposite in the chaff–the unusable husks of grain plants that are separated from the usable grain through the winnowing process. The wicked are light-weight. They are the barrier between the hungry and the foodstuff.
Verses 5-6 do not exactly parallel vs. 1 but there is some similarity between them. In verse , the blessed do not walk, stand, sit as the wicked do. The wicked do not stand (day of judgment), sit (in the assembly), and their walk "way" is destined to perish.