Poor manufacturing and non-compliance to specifications leads to quality issues and it can usually be detected during or right after production. The typical consequence is the disposal of or rework of some/all products.
Poor design and poor choice of materials lead to reliability issues, and they usually appear once the product is being used, often 3 to 12 months after shipment. Depending on the product application and warranty terms, this can lead to major customer dissatisfaction, poor reputation, extremely high costs and/or a recall, a class-action lawsuit, and/or injury or death of some users.