difference between inner join and equi join code example

Example 1: is natural and inner join same

A Inner Join is where 2 tables are joined on the basis of common columns 
mentioned in the ON clause. ... 
Inner join and natural join are almost same but there is a slight 
difference between them. The difference is in natural join no need to 
specify condition but in inner join condition is obligatory.

Example 2: difference between inner join vs outer join

INNER JOIN:
is used when retrieving data from multiple
tables and will return only matching data.

LEFT OUTER JOIN:
is used when retrieving data from
multiple tables and will return
left table and any matching right table records.

RIGHT OUTER JOIN:
is used when retrieving data from
multiple tables and will return right
table and any matching left table records

FULL OUTER JOIN:
is used when retrieving data from
multiple tables and will return both
table records, matching and non-matching.