This question deserves several "answers" aimed at different levels.
For elementary-school students, it is important to know that photosynthesis is how green plant cells trap sunlight to make sugar, and respiration is how all plant cells (and most other cells) break sugar down to release and use that stored energy.
At the high school level, we can add the understanding that all cells break down fuel molecules but only certain cells can use sun energy to create fuel molecules. Also, although the summary equations are sort of "the reverse of each other", the processes are not just "the same but completed in reverse", but involve enzymes and chemical reactions that are specific to the process of either photosynthesis or respiration.
In terms of ecological implications of deforestation as they relate to photosynthesis, it is not the lack of oxygen production that concerns us, because marine algae release much more oxygen per year than trees do. Our concern is that a lot of carbon, stored in wood, is released as carbon dioxide when wood is burned, adding to the impact of "greenhouse gases" on global average temperature.