select distinct
stock.teamType,
stock.teamName,
stock.leagueType
from teamNames stock
left join teams user on stock.teamName not in (user.teamName)
where user.membID = 20 and stock.leagueType = 'nfl'

select distinct  stock.teamType,  stock.teamName,  stock.leagueType
from teamNames stock
left join teams on stock.teamname = teams.teamname
and teams.membid = 20
where teams.teamname is null
and leaguetype = 'nfl'