resent_n (perhaps a spelling mistake, reset_n?) : This signal, as per standard convention should denote a active LOW reset signal. Means this signal will do a reset of the components connected to it when it is driven to LOW/'0' state.
tx_reset : As there is no "_n" here it denotes that the signal affects when it is in HIGH/"1" state.
Again it is a matter of convention as to who follows what.
Relation: assign tx_reset = ~resent_n ; // Verilog
I don't know how u are going to use them, but the above just shows an inverse relationship.