How vedic Mantras are different from Sthothras

How vedic mantras different from sthothras? 

Mantras are the vedic hymns which should be rendered or recited with suswara. Suswara contains Anudarthas and Udarthas i.e. Expansions and contractions. There is a rule that these must be chanted in a particular way by exactly replicating the swara with anudarthas and udarthas as mentioned in the literature. The swara frequency which invokes the diety. Wrong spell may not invoke the diety and also the wrong chanting sometimes creates an opposite meaning of the verse. That is why mantras are to be learnt under an expert and also to be recited as per the literature containing where the anudarthas and udarthes are to be spelled. So, veda mantras can only be recited after learning them. There is also a limitation that these should not be chanted at any time. these should be chanted at the time of organizing Karmaanushrana (Daily Rituals, Sandhya vandanam), yagnas, homams and also should be performed with internal and External cleanliness. 

 Sthothras are different from mantras. Sthothras do not contain any anudarthas and udarthas. Sthothras/ Stuthis are a praise to god delivered by the devotee when he really feels/ want to feel the presence of the diety. There is no particular tune for the sthothras. People can read this in their own tune even like... Only shiv tandava sthothra has been sung in more than 10 different tunes and also can read it any time after the bath.  There are different types of sthothras depending on the number of verses/ stanzas it contain. they are:-

1. Shatkams are the sthothras which contain only 6 verses/ stanzas.

2. Ashtotthara Sata nama sthothram contains 108 names. The name itself represents Asta + Utthara + Sata namam meaning 8 names after 100.

3. Astakams are of 8 verses/stanzas

4. Dwadasa Nama sthothrams contain 12 names of the diety.

5. Shodasa nama Sthothram contains 16 names of the diety

6.  Sahasranama sthothram are the verses which contain 1000 names of the diety.

7. Pancharatnams are sthothras with 5 verses/ stanzas.

and many more.

There are other sthothras which are not based on the number of verses and these sthothras came out when the poet/ devotee profoundly depicted the qualities and also specify the situation how the devotee is protected by the diety. Some of them are Karavalamba Stothram, Mantra Raja Pada stothra, Narasimha Stothram, Hayagreeva stothram etc. 

Thus "Stothras do not contain any swaram and can be read in any tune at any time with external and internal cleanliness."