They don't differ actually, you can use either expression and they are both correct. The formula of tener + participio is known as a verbal periphrasis. In this case 'tener' is acting as an auxiliary verb followed by a transitive verb (this periphrasis can only be formed with transitive verbs). In this case 'tener' has the exact same meaning as 'haber' in a compound tense:
Según tengo oído, es muy interesante.
Según he oído, es muy interesante.
Hmm... Usually this construction adds a touch or reiteration or insistence:
¡Lo tengo dicho!
¡Lo tengo decidido!
So, you may take that as little difference...?
I hope this helps!