Conflict between "min" function and "order by" clause?

 Why it's happens?

For "min" function 'IMPEDIMENTO' < 'IMÓVEL', in the contrary for "order by asc" clause 'IMPEDIMENTO' > 'IMÓVEL'.

--  min function: 'IMPEDIMENTO' < 'IMÓVEL'

select min(plv) from (

  SELECT 'IMÓVEL' plv from dual union

  SELECT 'IMPEDIMENTO' plv from dual

)

IMPEDIMENTO

-- order by clause: 'IMPEDIMENTO' > 'IMÓVEL'

SELECT 'IMÓVEL' plv from dual union

SELECT 'IMPEDIMENTO' plv from dual

order by plv asc

IMÓVEL

IMPEDIMENTO