What you are hearing are two different allophones of the same phoneme /o/.
In English /o/ and /ɒ/ are contrastive (e.g. rote vs rot), but Spanish only has one back-mid vowel /o/, and hence while open and close variants exist (and may be contextually conditioned to an extent), native speakers consider them the same sound. As such, they can be interchanged freely without change in meaning:
Some scholars, however, state that Spanish has eleven allophones: the close and mid vowels have close [i, u, e, o] and open [i̞, u̞, ɛ, ɔ] allophones
Mid back vowel /o/
- The close allophone is phonetically close-mid [o], and appears in open syllables, e.g. in the word como [ˈkomo] 'how'
- The open allophone is phonetically open-mid [ɔ], and appears:
- In closed syllables, e.g. in the word con [kɔn] 'with'
- In both open and closed syllables when contact with /r/, e.g. in the words corro [ˈkɔrɔ] 'I run', barro [ˈbarɔ] 'mud', and roble [ˈrɔβle] 'oak'
- In both open and closed syllables when before /x/, e.g. in the word ojo [ˈɔxo] 'eye'
- In the diphthong /oi/, e.g. in the word hoy [ɔi] 'today'
- In stressed position when preceded by /a/ and followed by either /ɾ/ or /l/, e.g. in the word ahora [ɑˈɔɾa̠] 'now'
This is analogous to /b/ having allophones [b] and [β̞] etc.
* As shown in the comments on this question.