Embedded text column versus referenced text

I am in the design phase of a new db so I cannot test queries using
explain/analyze yet, but regarding performance, is there any
difference in doing this:

CREATE TABLE something (name text, age smallint, ...other columns...,
comment text);

compared to this:

CREATE TABLE comments (id serial primary key, comment text);
CREATE TABLE something (name text, age smallint, ...other columns...,
comment integer REFERENCES comments(id));

?

The comments field will be used here and there but I expect it will
most often be NULL.


--
- Rikard